DNA – What, when, how, why – FAQs for beginners – 2024 Edition
You’ve got your DNA test back, and now you have a million questions to ask. Here is a list of some questions and answers that might help to get you started. Find out about Mickey Mouse, X DNA, Haplogroups, Clusters, DNAPainter and other third party tools, GEDmatch and much more…
Q: Help! I have my test results – what do I do now?
A: First thing most people do is look at their Ethnicity/Origins percentages – and are usually happy or confused! Check out some questions further down about ethnicity, and why it’s just an estimate. After that take a look at your match list. The match list is the most powerful part of a DNA test, it can help you confirm your family tree, breakdown brick-walls and solve unknown parentage cases such adoptions, foundlings & donor-conceived.
Your match list is ranked from highest match to lowest. Matches are categorised based on the amount of DNA you share, the more DNA you share the closer your relationship is.
Most sites will categorise a match for you but this is just an estimate or category – only genealogy will be able to determine the correct relationship. More about how DNA is measured, and how to work your match list, further down.
Q: Why do my ethnicity results not match my tree?
A: Ethnicity Estimates are just that “estimates”. They can relate to your ancestry from hundreds or even thousands of years ago and therefore will not match your paper trail from the genealogical time period. Ethnicity results are calculated by comparing you to a reference group of people (often called a reference panel). These are people that meet certain criteria requested by the test company (e.g. a reference person might have 4 grandparents all born within 50 miles of each other, all with known Ancestry in that region). Your DNA is compared to these people, often by scanning it several times and taking an average of the readings. Companies are continuing to update their reference panels and udating their ethnicity estimates. Ancestry have updated their estimates yearly and in 2022 added their powerful technology SideView(TM) where they split your ethnicity by parent. My Heritage have promised an ethnicity update “soon” for two years or more, but have only added to their genetic groups.
Q: I’ve tested at another company, or uploaded my DNA at another company, why are my results different?
A: Each test company has a different way of working out ethnicity (sometimes also called admixture). They all use a different reference panel and thereby arrange people into different regions. One company might have a category “Great Britain and Ireland” and another one might split that into two regions. If that particular company does not have a reference person for a specific region, then you will never get that region in your results – even if that is what you are 100%.
How do you know which one is accurate? Well none of them are “accurate”, although Ancestry is considered to be one of the best due to the work the scientists are doing and the continuing updates as they learn more.
Debbie Kennett did an excellent presentation at Family Tree Live in April 2019 that covered everything you need to know about Ethnicity – it is free here online at YouTube
Q: Should I download/upload my DNA to other sites? And which sites can I upload to?
A: Quite often in Facebook groups as soon as someone mentions they have their results back, people start commenting to “Download your raw file and upload to ….” . Whilst uploading to other sites can be a good idea, it can be easier to learn all the necessary details and jargon at your original test site before tackling other sites. Always check the T&Cs and privacy settings of the sites you want to upload to and ensure you are comfortable with them. ftDNA and GEDmatch also have law enforcement matching that you may want to opt-in or opt-out of (note that at GEDmatch you can not opt-out of unidentified human remains work). Many sites accept your DNA for free and some request payment for analysis and use of any tools they provide. Not all upload sites accept files from all test companies, so always check which company files can be uploaded. At this time the majority of Genetic Genealogists recommend testing with Ancestry first (largest database) and uploading to other sites starting with My Heritage
Stay away from the “spammy” sites that say they can match your autosomal DNA to ancient remains. This cannot be done and trying to match your modern DNA to ancient DNA is no more than “genetic astrology”. Jennifer Raff a Geneticist, Anthropologist & Science writer has a great article about this Genetic Astrology: When Ancient DNA Meets Ancestry Testing
Some common sites accepting DNA uploads:
- ftDNA there is a small fee to unlock their chromosome browser and access to My Origins. In 2023 ftDNA started rolling out the paternal haplogroup to males who have uploaded or tested with them. This rollout should complete in 2024. You do need to have unlocked the kit (or tested) with them to get his new feature,
- My Heritage – if uploaded before Dec 2018 then grandfathered into tools for free – after that date there is a fee for DNA tools (if you are not a subscriber). Sometimes they have had free upload days where you would also be grandfathered in. NB: if you test with My Heritage you will need a subscription to use all the DNA tools.
- LivingDNA (for matching only, but you can upgrade for the regional ethnicity breakdown for a fee. Matching is still limited with most people only having a small number). They are adding more features such as Viking DNA, see note above about comparing your autosomal DNA in this way and note there are additional fees.
- GEDmatch a public DNA database now owned by Verogen. The first site allowing Law Enforcement uploads for unidentified human remains and violent crimes. After several iterations of opt-in/opt-out currently you can opt out of criminal case but not unidentified human remains
Note: Ancestry and 23andMe do not accept uploads.
23andMe: At the end of 2023 23andMe had a widely published data breach which was conducted by bad actors who found leaked passwords linked to email addresses. Because many people use the same password and email address at every site, the bad actors were able to access accounts at 23andMe. DNA companies reacted quickly by adopting 2FA (two-factor authentication) to log into your account. Some companies also temporarily removed tools and downloads associated with segment data.
Ancestry: as of 02 February 2024 Ancestry requires a subscription to access some of their DNA tools. A small DNA Plus membership (at around £2 per month) is all that is required. For those wiht a subscription already there ar no changes to what you can do and see with your matches or with your managed kits.
Q: What does my match list mean, how do I use this information?
A: Your match list is usually arranged in order of highest match at the top and lowest match at the bottom. The test sites categorise your DNA into groups of cousins. Usually close family are listed as Immediate or Close Family, but the names of these categories can be different at each site. Although a match might be in say the 2nd cousin category, it does not mean this is a 2nd cousin. Various relationships fall into the same category due to the amount of DNA shared. Things such as half relationships, once or twice removed cousins, or a cousin marriage in that branch can mean the relationship is different than the category it is in. It is key to learn about how to predict a relationship based on the cM shared (cM stands for centimorgan, which is a complex measurement of the amount of DNA you share with someone).
At Ancestry you can find the predicted relationships by clicking on the cM amount in your match list – this will open up a table. The table shows the percentage of the time people sharing that amount of cM have the relationships shown in the list. The more DNA shared, the higher the cM amount and therefore the closer the relationship with the match.
Ancestry example:
Other ways to predict a relationship: For matches at other sites there is a third party resource called the Shared cM Project . There is more about this site in a couple of questions further on. Some sites (e.g. 23andMe) show your shared DNA as percentage rather than cM (although you can see the cM by looking further into the detail of your match if they are sharing that info with you). The SharedcM tool will take percentages as well as cM amount and also predict the relationships
Remember: The higher the cM amount the closer the most recent common ancestor (mrca) is.
Q: What does shared cM, largest cM and Segment numbers mean?
A: cM = centimorgan, a complex calculation to work out how much DNA you share. The test usually reports the total amount shared as either a cM number or a percentage (23andMe). They also usually show how many segments this includes. A segment is just a block of DNA you share. For most people the number of segments doesn’t really help determine a relationship. In distant relationships the number of segments is usually 1, i.e. just one small block of DNA is shared. The segments are often on one or more chromosomes – we’ll cover off chromosomes later. Most people can ignore segment numbers.
Some sites will show a third number, and that is the largest block or largest segment. So a match might be 40cM / 2 segments and 25cM longest block. This means the total amount of DNA Shared (the most meaningful number) is 40cM. The DNA is on 2 segments, one is 25cM (the longest block) and so the other must then be 15cM. The most relevant number is the amount of total shared cM as this will help you predict a relationship.
Note: DNA results of someone from an endogamous population will find the longest segment information the most useful. Endogamous populations are where there have been multiple cousin marriages over the generations (not to be confused with Pedigree Collapse which is where there is only one or two cousin marriages in a branch).
Q: How do I know what relationship the match is to me?
A: As above the test site will give you a prediction, ie 2nd cousin, 3rd cousin etc. But these are high level estimates only (more like a category) – based on the cM number. There are charts available to help you look at various possible relationships. The ISOGG wiki (International Society of Genetic Genealogy) has a huge amount of useful data, one of those is the Autosomal sharing statistics. The Autosomal DNA Statistics page has three charts, one that shows the various relationships in a family tree, one that shows the average likely relationship based on cM shared, and the last chart has a range of reported cM numbers by many people who have been confirming their DNA matches. The ranges are really helpful and can see that some cM amounts could mean many different relationships.
The third party tool previously mentioned in this blog is the SharedcM Project and is available in the tools section of the DNApainter site. This tool is really useful as you can type in the cM amount of your match and all the various possibilities will be highlighted. This is invaluable for genetic genealogists – so make sure you bookmark this site. As previously mentioned, if you have tested at Ancestry they have a chart that pops up when you click on the cM amount of your match and this is the preferred way to predict a relationship at Ancestry.
Once you have a predicted relationship, it is only by building family trees that you can work out exactly what the paper trail relationship is. Note that if your paper trail says someone is your second cousin, but the DNA does not fit into the range reported, then you have a mystery to solve. Maybe they are only your half second cousin, in this case look for other shared matches to see what might be going on, are they also matching lots of unexpected families? (or are you not matching a lot of your own family?). Unfortunately DNA can produce some surprises, not all of them good ones.
There are other relationship prediction tools available, My Heritage have built in their “cM explainer” tool and GEDmatch have included the dna-sci.com tool.
DNA research requires a lot of traditional tree building, so it helps to also get skilled up on traditional genealogy research. The actual relationship requires tree-building to establish exactly who your match is and their relationship to you. When the relationship is found through genealogy it should fit the cM amount.
Q: How can I work out if my match is paternal or maternal?
A: The test itself cannot tell you this* The best way to do this is to test a parent, as then any match that doesn’t match them, must be the other side. Of course not everyone can test a parent, so the next best is an aunt or uncle – they will help work out which matches are their side, but you cannot make the same assumption about those they do not match … some of those could still be their side, they just did not get the same DNA as your parent did (see the DNA inheritance question further on). First cousins can also be helpful as then you can pinpoint Grandparents that the match belongs to. Once you start confirming matches, shared matches will really help. As I’ve confirmed a lot of 3rd cousins as soon as a new close matches comes in I can click on shared matches and almost place the new match immediately in a tree branch, based on who they share DNA with in my list. Be aware that many genetic genealogists have found a high percentage of their small matches do not match either of their tested parents. This is called a “false positive” match as we can only get DNA from our parents. False positives start around 20cM and under at Ancestry, but as high as 45-50cM at My Heritage (due to the imputation technique they use for matching with uploaded kits).
A good blog on this topic from Debbie Kennett
*SideView (AncestryDNA) In 2022 Ancestry rolled out their powerful SideView tool for matches. The tool is able to establish (using DNA) which side your match is on and label them Parent 1 and Parent 2. This is the same tool that was used for rolling out the Ethnicity Estimate view by parent (again by Parent 1 and Parent 2). Users are able to update the label and call Parent 1 “Maternal” for example, which will in turn change Parent 2 to “Paternal”. It’s important to note that Parent 1 is NOT Maternal for all users, for some it will be Paternal, you need to decide. Some users have found that they initially labelled Parent 1 and 2 the wrong way round when looking at Ethnicity and have had to update the assignment. Note that Ancestry can not assign all matches and some will be “unassigned”. Assigning a side is done periodically so new tests may not have it for a while. Some users will get “both sides” matches and this often causes distress or confusion. A both sides match does not mean your parents are related, for example if a matches fathers side is related to your paternal side and their mother is related to your maternal side, they will be a both sides match to you. Sometimes a close relationship such as a half sibling might show as “both sides” which on face value appears unusual, but it may be two very small segments are related to your other parent side, more distant than you will be able to solve. Ancestry have announced that they are working on Grandparents sides, possibly due to roll out in 2024 (although no official communication has been made).
A good blog on this topic from “The DNA Geek”
Q: Will I match DNA with all my cousins?
A: No you won’t! Currently it’s never been found that a 2nd cousin will not share DNA, so if you are not sharing DNA with a known second cousin (who has also tested at the same site) then you have a mystery to solve, something is not right. But more distant than 2nd cousin and it’s possible to no longer have any DNA from the shared ancestor (see further down for details of how DNA inheritance works). This is generally around 10% of 3rd cousins who will not match you, up to 50% of 4th cousins and 70% of 5 cousins. It can vary of course, but these are high level numbers, so don’t be surprised if a known 4th cousin does not share DNA with you, it does not mean your paper trail is wrong and more research is needed to confirm the branch.
Info from ISOGG Wiki on Cousin Statistics
Q: Can I inherit DNA from my grandparents that has skipped my parents? Does DNA skip a generation?
A: No this is not biologically possible. Everybody gets a random 50% of their biological parents, which is a random “recombined” version of the DNA they got from their parents. This means that you do not end up with an exact 25% of your grandparents, and also explains why your siblings will have different DNA than you, in fact they will have a different ethnicity estimate and different matches (there will be some commonality though, and full siblings will share all their matches down to 2nd cousin level). Here is my chart showing how DNA inheritance works using colours to represent DNA.
And here are the ethnicity estimates, from the Ancestry site, for my Dad’s five siblings (proven full siblings)
Q: None of my matches seem to have family trees attached, and none of them are answering my messages – has DNA testing been a waste of time? Why do people bother to test and then not share anything?
A: Most certainly your test has not been a waste of time even if your matches do not have trees and do not reply to you. This has been the most common complaint from genetic genealogists over the past few years. Here are the cold hard facts: when someone got given a DNA test, or paid for a DNA test, or was requested by a family member to do a DNA test … at no time during that process were they buying into communicating with other people, replying to messages, sharing their tree, or for some even bothering to look at it again after they first got it! It’s not for us to wonder why, or have unrealistic expectations that everyone is like us and want to get about researching their tree. Also remember that many testers are adoptees and foundlings, firstly they do not have a tree to share, and secondly they are often warned off communicating too much about being an adoptee, sadly not everyone wants to help them. So what can we do about it? Well as it turns out, actually quite a lot!! If you have a match with a private tree there are tricks to figure those out too, check the next question for private trees .
SLEUTHING, how to become a Genetic Detective 🕵️ : Researching DNA matches without trees – my long list of things to do:
– open the dna profile page and check if they do have a tree but just not linked (Ancestry) <- about 75% of the people with no trees, do actually have a tree. (If you’ve not linked your DNA to a tree.. go and do it now!)
– go to their main profile page at Ancestry, look for clues as to how long they have been researching (if a long time, then they may have a tree on another site)
– check their main page for age range and location … sometimes people put a LOT of really useful info on their profile
– google their name/ profile name using some of the clues you may have found – looking for possible hits on who they are. Learn to do advanced google searches. For ftDNA & GEDmatch matches google their email address to see if they have a tree somewhere else, or family information online .
– write all your clues down, tick them off or cross them out as you validate them/invalidate them.
– look for possible trees at wikitree, geni, genes reunited, My Heritage, FMP, etc..
– if you’ve now established a possible name, check 192 dot com, white pages, electoral rolls, pipl, etc … where you might find details about them
– search for Online obituary’s (especially useful if the match is in the US as they often list all their family in detail)
– bear in mind woman testers often use their married name
– on the matches DNA profile page, click on “shared matches”… who else do they match ? You might be able to research the group of shared matches together, working off clues from the shared matches trees. Shared Matches can be gold when trying to identify and solve a match without a tree.
– if they are at Ancestry check if they’ve uploaded to My Heritage, ftDNA or GEDmatch.. can you identify them there (if you can now you will have an email address, for more google searching) .. and also a new set of people who match you both
-start building a “research” tree for them , keep it private and unsearchable .. it’s “quick and dirty” so add hints, extra people, whatever you need to try and establish who your match is and their ancestors. This type of tree is often called a “Quick & Dirty tree” – due to the fact you are doing it quickly (accept hints if using an online tree), and dirty in that you are not looking for sources at this point you are copying other peoples tree or using hints. It is better to have just one “research tree” so add all matches into it and edit their relationships to make them standalone. Build out the tree of your match to find the common ancestor.
BUT … Keep in mind you may get nowhere, in which case you research hasn’t gone to waste … maybe tomorrow they decide to create a tree, or they get a new shared match that opens up better clues. (Keep your notes! I add mine to the matches name in my Research tree).
As you start pulling together your hypothesis of who the match is, and how they relate to you, always go back and try and disprove it, don’t get caught out with confirmation bias where you only look for clues to prove your theory, more importantly look for clues to disprove it! This includes once you find the match, to go back and check that the DNA could not have come from another relative!
If you are looking at what the predicted relationship might be, see the earlier questions on how to do this.
Recently some people have challenged the privacy and ethics of researching people in this way. In no way are you doing anything illegal by searching public information to find out about your match (your cousin in fact). But please keep your research private, if you come across something your match (your cousin) probably doesn’t want published, please think of them and be ethical about sharing information you’ve discovered. Any speculative trees you make should be private and unsearchable. If a situation seems delicate, please treat it as such.
Here are some more resources on how to identify your match and/or create quick and dirty trees
- https://www.rootstech.org/video/a-dna-match-with-no-tree-no-problem
- https://www.familytreemagazine.com/premium/no-tree-dna-matches/
- Crista Cowen (Ancestry) using quick and dirty trees https://youtu.be/VP8rUlZbmeA
- https://thegeneticgenealogist.com/2017/03/11/are-you-doing-everything-to-identify-your-matches/
- Look out for my talk “The Genetic Detective”
Q: My match has a tree, but it’s private and they are not responding to messages, how can I work with this match?
A: The first thing you should know about private trees is that when you search your Ancestry matches, the results include private trees. So by quickly doing a few searches, using names in your tree, you can establish which names they also have in that private tree. This can help to confirm a branch they may be related on. Also use some of the tricks and tips above and especially look at Shared Matches … this can tease out exactly where this match might sit in your tree.
Q: At Ancestry I have Common Ancestor Hints and ThruLines – can I just accept these as how I share DNA with my match.
A: In short No. These are tree hints, the Ancestry algorithm has found that you and your match has someone that looks the same in their tree, or the Ancestry algorithm has been able to stitch together a genealogical tree from all the trees they have in their database. These are not “DNA Hints” – they are “Tree Hints” so beware.
The common ancestor hints & the ThruLines pick up an ancestor that it thinks is both in your tree and your ancestors tree, but sometimes the “same name” isn’t actually the same person, so you must check. Also if your match just copied your tree then you will, of course, also have the same name in your tree. My old saying is that if you have Mickey and Minnie Mouse in your tree and your match copies it, then you will get a Common Ancestor hint and a ThruLine showing you are descended from the Mouse family – of course you are not.
So all hints require further research BUT they are often a very good place to start. They can be excellent, but they can also be wrong – so please take care to always do more research on a ThruLine.
!Do not fall into the trap of moving your DNA around to try and manipulate ThruLines, if your match sees this they may copy your tree and bingo you will get a ThruLine. This warning also refers to adding speculative people to your tree. We have enough and trees at Ancestry without genetic genealogists trying to manipulate the system and add speculative ancestors.
Crista Cowen (Ancestry) has presented a great video on What are Thru lines
Q: I’ve uploaded to GEDmatch, but I’m lost and it’s confusing, what does it all mean?
A: GEDmatch is a public DNA database that was previously run by volunteers, it is more technical than the test sites themselves and can often appear confusing. At the end of 2019 GEDMatch was sold to Verogen and at the start of 2023 Verogen was bought by Quiagen. Details here. During 2019 GEDMatch came under fire for allowing Law Enforcement use of their database – without properly alerting their users. Much of the Law Enforcement advancement into Genetic Genealogy came around the time the Golden State Killer was identified by using genetic genealogy. Many other doe cases & law enforcement cases have followed – often with much discussion from the Genealogy community who have been using DNA databases for genealogy and not expecting their use for law enforcement. Everyone has different opinions on what should & shouldn’t be allowed. Ethically this is something each genetic genealogist needs to determine for themselves. Genetic Genealogists should also act ethically with kits they manage for other people – is there Informed Consent for your testers and have they agreed to what you do with their DNA data. Later ftDNA went on to also allow Law Enforcement to match kits in their database. At both ftDNA & GEDMatch you can opt-in or opt-out of Law Enforcement matching (at GEDmatch you cannot opt-out of Unidentified Human Remains matching).
https://isogg.org/wiki/GEDmatch
Q: What is X DNA and how can I use it in my research?
A: X DNA is the DNA on the the X chromosome (chromosome 23) . We all have 23 pairs of chromosomes from our parents (22 of these are called the Autosomes, hence the term Autosomal DNA) – one of each chromosome from our mother and one of each from our father. A mother passes a recombined X DNA from her two X chromosomes and a father determines the sex of a baby by either handing down an X chromosome for a biological female, or a Y chromosome for a biological male. This means some one born male only has one X chromosome and he must have got that from his mother. This makes it X DNA a useful tool to help sorting out your matches, as if you are a male tester and match someone that shares significant DNA on the X chromosome, then it must come from your maternal side. However the X chromosome should be used carefully – some experts say that the X DNA should be at least 15cM before being meaningful, and if you don’t share any DNA other than X, then it may be a very distant match that you would be chasing. When you have a match with X DNA you can fill out an “inheritance chart” to help highlight where the DNA could have come from (as it cannot be passed from a father to son). There are two charts, one for a Female as she will have X DNA from her mother and father) and one for a Male (as he can only have X DNA from his mother).
Blaine Bettinger has a great blog on this topic, including the X Inheritance charts that you can use
Q: I’m working with my match and we both have well researched trees, why can we not find the common ancestor, or why can we not find a common surname?
A: Here is my list of reasons why you may not find a common ancestor.
If you cannot figure out how you are related to somebody, because their tree and your tree do not have the same names in it – then it could be for one of the following reasons:
1. Your tree is wrong or does not go far enough back to find a common ancestor. Keep building out your tree, you should be able to get a rough prediction of where the most recent common ancestor is, based on the amount (cM) of DNA you share.
2. Their tree is wrong or does not go far enough back to find a common ancestor … in this case you need to do the research in their tree yourself. I do this by starting a private (and unsearchable tree), and starting with their parents or grandparents build up the tree trying to find a location in common. Don’t get too hung up on surnames, look for places where your ancestors have crossed paths
3. There is an NPE (Non Paternal Event, sometimes these days called MPE, Misattributed Parent Event or similar) in your tree. If you are finding a lot of trees that don’t match your own, or family that have tested that do not match you as expected, then maybe there is a broken line where the father named in the source document is not the actual biological father.
4. There is an NPE in the matches tree. In this case look at shared matches, and see if you can find where the matches tree might be wrong. In these cases it’s often easier to contact the match and try and research with them.
5. The common ancestor is back before the genealogical time frame, i.e. a segment of DNA has passed through the generations unbroken and you will never find the common ancestor. These segments of DNA are often called sticky segments (although that term is going out of favour). There are specific known areas that are prone to this (called known pile up regions). Ancestry’s matching algorithm does remove those.
6. The DNA match is false, a small match under say 10cM may just be a coincidence rather than a real match. If you have tested both parents you can easily find a false positive match, because they will not either of your parents.
Q; The same match at another site seems to share a different amount of DNA with me – how can that be?
A: Each test site uses a different matching algorithm to create what they call a match. Ancestry has a sophisticated algorithm they call Timber and it down-weights segments of DNA that are considered to be shared due to a population rather than a recent common ancestor. This means that the Ancestry site might report a lower number than another company.
Q: What is a Haplogroup? And how do I find mine?
A: Haplogroups https://isogg.org/wiki/Haplogroup come in two types, maternal and paternal, and they pertain to our ‘deep ancestry’ ie they show our maternal (mother’s mother’s mother’s… line) or paternal line (father’s father’s father’s line …). The haplogroup is a type of “family name” for people who have similar DNA “Mutations” (mutations shouldn’t be considered bad here, it just means the code you have at specific places in your DNA) .
Everybody can be assigned a maternal haplogroup if they test their mitochondrial DNA. This a special type of DNA that surrounds the nucleus of the cell, it is not on a chromosome. Everybody has mitochondrial DNA (MtDNA) but they only get it from their mothers. Men do not pass down any MtDNA . So males and females can take the test, and sometimes a high level haplogroup can be assigned by testing a very small part of your mtDNA and this is often combined with a autosomal DNA test (23andMe and LivingDNA do this). Usually when this is done you would not get any MtDNA matches, just the high level haplogroup. ftDNA do full MtDNA tests that give you a final haplogroup and matches. But one note of caution with MtDNA tests, MtDNA mutates very slowly so when you get an extremely close match, it could mean the most recent common ancestor lived over 1,000 years ago. So this may not be the best test to take if you are looking for matches within the genealogical timeframe. More info here at ISOGG https://isogg.org/wiki/Mitochondrial_DNA_haplogroup
The second type of haplogroup comes from the Y chromosome, and therefore the test is only available for males. Many woman ask their brothers, fathers, or uncles to take the test for them. Like MtDNA a high level haplogroup can be estimated, but more detailed testing is required to get a more detailed haplogroup. FtDNA also offer Y DNA tests, both the marker test (STRs) and SNP tests. When you match someone with the same haplogroup, this does NOT mean you match each other within the genealogical timeframe, or that you even match each other on your father’s father’s father’s line. Within your family tree, you would have many many haplogroups, but when testing yourself you are only seeing the very limited lines of father’s father’s father’s line… or mother’s mother’s mother’s lines. Haplogroups are amazing and interesting, as are Y DNA and MtDNA tests, so it’s well worth finding out more if you want to go down this route. More great information on Y DNA tests here from ISOGG https://isogg.org/wiki/Y_chromosome_DNA_tests
At the end of 2023 ftDNA started rolling out Paternal haplogroups for people who had tested with them (Family Finder) and people who had uploaded their autosomal DNA test. This will be for males only and will require an uploaded kit to be unlocked (see the upload question further up the blog).
Q: I’ve found several matches that all match me at the same location on the same chromosome – does this mean we all have the same common ancestor?
A: You cannot answer that until you do further steps. You must do one on one matching with each match (with each other) in turn. So for 4 matches you need to check A-B, A-C, A-D, B-C, B-D, C-D. This is because you are looking at a pair of chromosomes stacked on top of one another, your paternal chromosome and your maternal chromosome. Some of the matches will be paternal to you (they will all match each other, but not everyone) and some will be maternal to you (they will match each other but not anyone in the first group). Each group can now be considered to have the same common ancestor, but you need to figure out which group is maternal and which is paternal. They must all overlap for at least 7cM or more to be considered a real match. Note that this can be easily done at GEDMatch, My Heritage and 23andMe where you can check your matches against one another, but at ftDNA you can only check matches against yourself! Ftdna have a tool called the matrix which can be used to see if you all match each other, however you can only make an assumption as the matrix does not show the chromosome number, just high level whether someone matches another. At Ancestry you cannot see any chromosome or segment data, therefore you need to use Shared Matches, but again you will not be able to confirm if they are all the same common ancestor.
Q: How small a match should I go chasing to find a common ancestor?
A: It is personal preference really. Anything under 7cM is considered to be more likely to be a false positive. I personally don’t chase matches that are likely more distant than about 4th – 5th cousin, this is firstly due to the number of matches I have across many kits, but also the chances of actually finding a common ancestor at that range becomes much harder … bearing in mind that source documents are harder to find, women’s maiden names may not be recorded, and there is more chance of errors on trees, and NPEs causing confusion. Even if you find a common ancestor with a potential 8th cousin (because you have the same tree, bear in mind the Mickey Mouse theory above, but also at such a small amount of shared DNA you cannot confirm the DNA was from that particular ancestor and not another unknown ancestor branch on your tree). I leave small matches alone, unless they have good genealogy and I do use that to place them in my tree (however I am fully aware the DNA does not necessarily confirm that genealogical connection).
Here is a great blog from Blaine Bettinger regarding small matches a small segment round- up and a fantastic follow-up to this is his 2022 An In-Depth Analysis of the Use of Small Segments as Genealogical Evidence.
Q: There is no chromosome browser at Ancestry – do I need one?
A: Although a chromosome browser can be useful to solve some very particular puzzles, for the majority of genetic genealogy work you will not need a chromosome browser. The best and most productive method of using your DNA matches is to work with your DNA groups of shared matches, build a quick & dirty tree and see how they are connected. The common ancestor of a group of shared matches is most likely your common ancestor.
A group of matches that have a common ancestor do not necessarily all share the same segments on a chromosome. Sharing all the same segments on the same chromosome is called “Triangulation”, but again using triangulated segments is not the most productive method of genetic genealogy.
An interesting blog by Diahan Southard on using Chromosome Browsers
Q: I’ve heard about Clusters and the Dana Leeds method – what is that about?
A: Using Shared Matches has become the powerhouse of DNA research and “Clustering” is the term used when working with groups of shared matches. Generally speaking a group of matches that also match each other is likely to have the same common ancestor. This common ancestor is also likely to be your common ancestor. The theory is that if you solve the group (or cluster) of shared matches, you can work out your connection to them. If the common ancestor of the group is not in your tree, you may have a mystery to solve.
Finding shared matches is quite easy on most of the test sites. Ancestry and My Heritage go a step further and allow you to colour code your matches into groups using coloured dots. This can be really helpful as you can colour code your matches however you like. I suggest you colour code them based on the group of shared matches. One method of clustering to find 4 groups of matches for each of your grandparent branches was documented by Dana Leeds in a series of blogs. You take your top match (starting around 400cM), check the shared matches and then colour code them all the same colour – thereby creating a cluster ready for you to try and identify yours (and their) common ancestor. The Leeds method suggests starting with matches of 400cM and clustering to 90cM. If you don’t have many high matches it is better to cluster down to about 40cM or even 30cM. Any lower and it can become quite complicated. These clusters or groups are like “Genetic Networks” within your match list. The “Leeds Method” used a spreadsheet (Google sheets or excel are good spreadsheet applications) but it can be much simpler just using the coloured dot system.
A great third party tool available to automate clustering was developed by EJ Blom at Genetic Affairs. This same tool is embedded in the My Heritage tools (“Auto Clustering”) and is also available via the Tier 1 tools at GEDMatch. Genetic Affairs is also supported by a Facebook User Group. This is not applicable to the Ancestry site.
Clustering your shared matches is going to be the most useful first part of your DNA research, but don’t over-think it, the real work is in building trees … Genetic Genealogy is all about the Genealogy!
During 2020 I recorded a video on how to do clustering and use this method to solve your matches, and to solve unknown parentage. It is available in the featured section of my Facebook group (link below) and also on my YouTube channel
https://youtu.be/5yfAfpANktg
Q: What is DNAPainter – I hear this all the time, but what actually is it?
A: One of the most useful third party sites is DNAPainter , it is a fantastic site that houses not just the DNAPainter tool itself but also the SharedcM Project chart, the WATO (What Are The Odds) tool and more.
- The actual DNAPainter tool is for mapping your chromosomes. This means taking segment data where you share with your match and “painting” it on to a blank chromosome. If you know the common ancestor of that match, then you now know that the DNA on that part of your Chromosome is from that ancestor. You need segment data to do chromosome mapping. Segment data is available at ftDNA, My Heritage, GEDMatch and 23andMe (but not at Ancestry). The tool is supported by a Facebook User Group.
- WATO – this tool is fantastic to help work out the mathematics of placing yourself amongst your DNA matches. Invaluable if you do not know you connect to a group/cluster of matches. You start the tool by adding the common ancestor of the group and charting out how your matches connect to that ancestor. Then you add various hypothesis points to the chart (or click the button to have them automatically added)- each hypothesis gives you a score against the previous hypothesis – as you work on it you can gain more clarity about where you are likely to fit with this cluster. The tool is supported by a Facebook User Group.
Some other helpful links:
– Acronyms – here is a list of them all https://isogg.org/wiki/Abbreviations
– GEDmatch admixture calculators – a great explanatory blog http://genealogical-musings.blogspot.co.uk/2017/04/finally-gedmatch-admixture-guide.html
Some of my favourite blogs and bloggers:
https://mobile.twitter.com/genealogylass?lang=en
An unscripted interview with me at Family Tree Live
Some of my beginners talks online Please note some of these were filmed with a live audience and there will be some, hopefully minimal, background noise
Testing for Genealogy the basics
Making the Most of your DNA test
Autosomal DNA testing for beginners
I am also on X (formerly Twitter) as @donnasr
And of course my Facebook Group that was set up to help both beginners and advanced users, specialising in those with UK ancestry.
https://www.facebook.com/groups/AncestryUKDNA
You can contact me at ds.rutherford@gmail.com – I do take some private clients and I’m always interested in discussing foundling cases and will work on those pro-bono. I specialise in solving tricky and complex DNA cases.
Send to KindleBlack Friday, Cyber Monday and other holiday season sales
Ancestry
“Cyber Sale” – Check the site for details ancestry.co.uk/ currently £49 Plus Shipping. Offer ends 29 November 2021 11:59pm
Check at Amazon as deals there also and they may exclude shipping – Currently £49, no shipping for Prime members.
23andMe
Sales on their Ancestry +Traits test and the Health + Ancestry test
Note that 23andMe now offer UK members their 23andMe+ Service, this includes additional health reporting (currently £19/year – no discounts). Limit 3 kits. Offer ends 29 November 2021
Check at Amazon who also sell 23andMe but currently showing at full price
MyHeritage
“Black Friday DNA Sale” – kits are £39 and free shipping if buying 2 or more kits.
Sales ends “soon”
Family Tree DNA (ftDNA)
Various Black Friday sale prices on Family Ancestry (“Family Finder” Autosomal DNA test), Maternal Ancestry (mtDNA), Paternal Ancestry (Y DNA – biological male only test)
Note: prices at ftDNA are USD
Y DNA sale (Paternal Ancestry). Note this is the surname line, the unbroken patrilineal line. https://www.familytreedna.com/products/y-dna
Bundles at ftDNA https://www.familytreedna.com/products
Upgrades at ftDNA. If you’ve already purchased at test, then you can upgrade it to an additional test without sending a new sample in
Note: All prices at ftDNA are in US Dollars
Send to KindleGetting started with GEDMatch, basics for newbies
Basics of GEDmatch:
1. Run a one-to-many report for your “kit”. Everyone who uploads their raw DNA files to gedmatch gets allocated a kit number (starts with A if it was from Ancestry T if from ftDNA, and M if from 23andMe)
2. When you run the report the system goes off and matches you against all the other people in the database. It will return a page of 2000 matches, sorted by closeness of predicted relationship (closest matches at the top).
3. To do further matching and get more details on how the match is made, run a one to one report using your kit number and the matches kit number. At the bottom of your one to one report you will see an “mrca” number. Mrca means most recent common ancestor. It will give a number, e.g. 3. This means that based on the amount of shared DNA the system predicts your most recent common ancestor with your match is 3 generations back. Count your parent gen as 1, then grandparents 2, so 3 means that system predicts you share great grandparents (based on the amount of shared DNA. – there can of course be other relationships that share about the same amount, so it’s just a prediction based on numbers, to work out the exact relationship you need to build a tree)
Shared DNA is calculated in an amount of cM (centimorgans). The more cM you share the closer the relationship is. Small amounts of cM shared may just be a coincidence, so stick to looking at matches with a high number of matching shared DNA.
Gedmatch allows you to see where you match someone, exactly which chromosome . This is helpful when trying to find a lot of matches all in common (if you all match each other on the same chromosome at the same location then you all have the same common ancestor). But bear in mind you have two of each chromosome (one from dad, one from mum), so ALWAYS check your matches using the one to one report to check that each match , matches each other before you assume they are all from a common ancestor (some will be a common ancestor on the maternal chromosome and some will be from a common ancestor on the paternal chromosome)
Some people have uploaded a gedcom family tree, and you can do a “user lookup” from the links on the left hand side of the gedmatch home page, it will then show you if that user has a gedcom (or run the DNA+gedcom report to find all matches that have gedcom).
When you are ready to contact a match, you can email them. Bear in mind you can google their email address and it might provide you some clues as to who they are and if they have a tree online somewhere. (Keep in mind that some kits are administrated by someone other than who did the test)
Only concentrate on matches near the top of your matching report, otherwise you could be looking for a needle in a haystack (I only work with matches greater than about 20 or 30cM).
Hope that gets you started.
Send to KindlePut the kettle on, lets sit down and talk about DNA (*for newbies only)
I’ve recently started a journey of using DNA to further my family tree research. I have an extensive paper trail family tree from many years of research, but I was really interested in what science could offer in terms of using a DNA test to find cousins and confirm who I thought were my family. DNA testing is relatively new for genealogical purposes but it has been of huge interest to adoptees (of which I’m not – I know my biological family) for obvious reasons. The goal of DNA testing for genealogical purposes is to find the most recent common ancestor shared by you and the matches returned by the DNA testing company.
At first it seemed sensible enough, if DNA could prove who committed a crime, and prove paternity then surely it could be used to find family and prove family connections. Sure enough there is a particular type of testing that can be used for genealogical purposes. There are many types of DNA tests (not just genealogical ones) – but the one used for family history purposes is called an Autosomal DNA test. Basically this is not a full sequencing of our genome (that would cost an awful lot of money!) but it is a test that, put simply, just looks at what makes us different from each other. These differences we all have (red hair, big nose, long legs…) are inherited from our biological families. Within our DNA there are areas that have mutated over the years to create these differences in the human race. As DNA gets more and more randomised over each generation (and in fact more mutations start to occur), we can only really compare our differences from the past 5 or 6 generations – after that it is too mixed up and randomised to be useful for genealogical purposes (remember I’m only talking about genealogical DNA tests).
I needed to learn about how DNA is inherited so that I could understand what the tests were telling me. We inherit 50% of our father’s DNA and 50% of our mother’s DNA – after that DNA is quite random and mixed up. So the 50% of our mother’s DNA could be made up of a large portion of her mother and a small portion of her father. Although she inherited 50% of each parent it has been recombined before being passed on. So it is incorrect to assume that your DNA is exactly 25% of each grandparent, but you do know for sure that you have exactly 50% of each of your parents. If you google “DNA inheritance” you’ll find lots of charts that explain this is much more detail.
I took the DNA test initially at Ancestry – it was all quite simple, spit into a tube and mix in some stabilising solution (supplied) and put it back in the special postage box and drop it off at the post office. Samples are sent off to labs in the USA for testing in a pre-paid box that comes with the sample tube. It takes a few weeks for the sample to be processed, but after much anticipation the results were in. Initially when getting results, like most people I dived straight into what my ethnicity was – I was over 90% British, 5% Irish and 2% Finnish (so far the Finnish part is still a mystery – but I will touch on Ethnicity results later). Once I got over the excitement of ethnicity results I suddenly realised I was faced with a very long list of names of people who appeared to be related to me. These matches were listed in the order of closest matches (in Ancestry terms these were given a “Possible range” such as “Close family – 1st cousins” through to more distant cousins (“5th-8th cousins”). But that was it, what did it all mean? and how was I supposed to figure this out – none of these people (there were hundreds of them) were known to me. Now I have been doing family research for many years, so I was expecting (I think) to just see names that I already had in my tree, and simply match up that these cousins had the same paper trail as me, and we could confirm my years of research. It was NOT that simple, and I suddenly realised that I needed to understand more about how we matched and what made some people a closer match. How on earth would I sort all this out? Turns out I wasn’t the only person dazed and confused with my DNA test results! I joined a few facebook groups, started watching some videos and reading about genetics and DNA testing, and slowly the clouds cleared but it certainly is much more complex than I initially thought. I’m well on the way to confirming a lot of different matches and below is more about my journey. This is not written in a technical or scientific manner – I’ve attempted to write this as if we were just having a chat about it. Apologies if I’ve skimmed over some technical areas, or made a broad sweeping statement on something that is much more complex, it is my attempt to simplify the more complex information, with the hope that people may go on to learn more about the complexities of the subject (it really is fascinating).
Having learnt a bit about DNA, the next thing I went on to learn about was something about chromosomes – I had no idea how these worked, but they are basically what hold all this DNA. We have 46 chromosomes, 23 from each biological parent. Of the 23 chromosomes from each parent, 22 (44 in total) of them are called the “autosomes” (this is where the name autosomal test comes from). Chromosomes have areas where each human is different – these differences are called SNPs. (pronounced snips). If we are closely related to someone our differences are the same as their differences (ie red hair, big nose, long legs). The SNPs are the areas of DNA that are used for genealogical purposes and the various SNPs (differences) that are tested can be measured in a certain way that makes them comparable for close relatives. The measure used by the testing companies is a centiMorgan (cM) . This is not a simple measurement like inches, or a count of things. It’s a mathematical formula that works out what they call “genetic distance”. I found out that initially all I needed to know was that the more shared cM (the higher the number), the closer the match I was to someone (and the more likely we had a shared ancestor). There are in fact two cM numbers that are relevant in our DNA testing, the “total shared cM” and the “largest cM” sometimes called “longest block” (this is largest segment of DNA, or to put it simply where the shared DNA is all together and not split up). Full siblings have a lot of DNA in common (because they both got 50% from the same parents), they have a shared cM of around 2,550 but they are not identical because of the DNA inheritance and how the DNA passed on is randomised. Second cousins match at around 212.5cM. Sites like ISOGG wiki have charts that help us work out what the likely relationship of a match is, based on the total shared cM. These charts become invaluable to search for a common ancestor of you and your match as you need to know if you are looking for a common ancestor 1 generation back or 4 generations back. The higher the number the closer the match. http://www.isogg.org/wiki/Autosomal_DNA_statistics
For my test at ancestry, I realised that ancestry do not show any cM numbers [edit Jan/2016: from late 2015 Ancestry do now provide a total cM number for each match]. However they do produce a chart that shows what the cM numbers must be for them to class our matches into various categories of confidence and likely relationship (It is available on the Ancestry site). One of the other big 3 testing sites is ftDNA (familytreeDNA) – they do show all the cM numbers for your matches – on the initial page of matches they show the total shared cM and then by clicking below the match name you’ll see more detail including the more important longest block cM. 23andMe the other of the big 3, requires the match to allow you to see your matching details, they are not displayed initially. I could have just sat back and looked at the ancestry results, compared the detail they did let me see (and they do have a lot of information, it’s just they don’t share “the numbers”) and contact my matches to see if we could work out together who our common ancestor might be. Ancestry do offer some automated tools, they will give you a “hint” if your DNA match has the same paper trail as you, and they will also show you on a map where your matches paper trail locations are. They also show you a list of the surnames in the tree of your match. This assumes that the person who matches you, also actually has a public tree or has even done their family tree. It started to emerge that many of the testing sites do have problems in that people were not necessarily sharing their trees or replying to contact. Each of the testing sites vary in terms of what you can see or do with your DNA results. So although I had now learnt all about understanding autosomal DNA results, I was coming up against brickwalls in terms of knowing and tracking down who these matches were, let alone who our shared ancestor was.
My knight in shining armour was a site called GEDmatch (gedmatch.com). GEDmatch is run by volunteers and is free, it provides tools to help examine DNA matches closer, by providing detailed cM numbers and chromsome browsers to drill down to the detail of how you match someone. Up until this point the only site I had seen a chromosome browser on, was ftDNA. Ancestry do not have a chromosome browser and 23andMe do, but it requires your match to allow you to see their DNA results first. To be able to use GEDmatch I needed to send them (upload) my DNA results – this was actually very simple. Each of the big 3 testing sites allow you to download your DNA file, and GEDmatch is setup to take this download file and process it into their database – it is just a simple matter of registering on the site and going through their upload process (follow the links on their home page – you need to register first). Although by this stage I had test results at each of the big 3 sites, it is only necessary to upload one of your files (for the purposes of GEDmatch they are all identical). Speaking of testing on all sites, ftDNA site (www.familytreedna.com) offers an “autosomal transfer” – this means that if you have a test on ancestry you can upload it to ftDNA and they will process it into their database as if you had the test there. There is a cost for this but it is very small in comparison to actually doing their test. This means you can be in both the Ancestry and ftDNA database for the price of 1 test and a small additional fee. A bargain! I tested with 23andMe directly as I was becoming more and more interested in DNA and wanted to see how their tests and site worked. They have some have fun additions to their results including your Neanderthal percentage and other various things. 23andMe also offer heath testing (not available in all countries). I found this very interesting but will not be covering that in this blog post. All I would say is if you have any questions or concerns regarding health reports from your DNA test, then you need to discuss them with health professionals and not genealogists. If you want health results and have not tested with 23andMe, there are other sites available – you can google for them, but Promethease is a suitable alternative and you can upload your DNA file for a comprehensive health result for a very small price.
So back to GEDmatch – after a few days (although now it can sometimes only take a few hours) my data was processed and able to be analysed in a “‘One-to-Many’ matches” report. You can find this and other reports on the GEDmatch home page once you have registered and logged in. GEDmatch is more of a technical site than perhaps the nice user friendly interface of the testing sites themselves. There are some very good blogs about using GEDMatch but I will cover some of the tools I’ve used in the most simple way I can. There are 2 reports I’m going to cover – these are the ones that you will use the most when you first get started. The first report to run is the One-To-Many matches report. When you click on it the page opens and looks a bit complex to start with – but there is only one field you need to fill in and that is your KIT number. A KIT number is assigned to you by GEDmatch when go through the process of uploading your DNA file. You can upload files from any other relatives that you have tested and uploaded as well – they will all be available on the front page when you log in – each with their own KIT number. I now have both my maternal uncle and my son on GEDMatch [edit: Jan/2016 – I know have mother, sister, and several uncles on GEDMatch – I am truly addicted]. I’ll explain why you might want to test more family members – when you see your matches, you are unable to tell where they might match you, is a cousin on your fathers side or your mothers side? There is no way that the test can work this out for you. If you tested your mother for example, you would see that many of your cousin matches are also her cousin matches. (when I say cousin it may be first, second, third, 2nd 1 times removed etc…). When you looked at your mothers matches you know that that match comes from her side of the family. You can safely assume that the majority of matches that don’t match her must be from your fathers side. (I say the majority, because there could be several matches where the cM numbers are low and these may be coincidental that you match them, rather than because you have inherited that particular DNA from a common ancestor).
GEDmatch reports can be quite confusing to start with as they look like spreadsheets with lots of numbers. For an excel fan like me that was quite exciting, but I imagine that anyone who may not be so technical or mathematical, it might look hideously confusing. So lets breakdown what we actually see on these reports. By running a GEDMatch many to one report, you will get a list of 1500 matches – these are people that match your DNA and have also uploaded to GEDMatch. You can tell where these people did the actual test as the first column lists their kit number – a kit starting with A means it was an ancestry test, F for ftDNA and M for 23andMe tests. This can be useful to know if you are researching someone and want to try and look for them on the site they originally tested on. Especially useful if you have tested on the same site as them. Going across the page of the GEDmatch report you want to look across for those 2 important numbers – total cM and largest cM. GEDmatch will sort the report with the largest shared cM at the top. I like to re-sort the page by the largest cM, and it can be done by just clicking the little arrows in the top of that cell where the column name is. The next step I took when I first ran my reports, was to download this list of people to an excel spreadsheet. You can do this by just highlighting them all on your computer and copying and pasting them to a spreadsheet. The reason I did this was because they were now on my own computer, but also it meant I could add some columns to write notes next to each match, or I could highlight the names I knew, or the names I was more interested in researching. Because I couldn’t possible research 1500 names, I extracted the top few matches and put them into a new sheet – I called these my TOP MATCHES. I’ve since added to my top matches by adding matches from the test sites (although several of them were already in GEDmatch, so I only added those that weren’t – and again kept it only to the closest relationships). My Top Matches list is where I spend all my time now – I’m only working on matches that have the closest match, I’m not bothering (at the moment) with all the more distant cousins. It’s worth noting that 2nd cousins mean shared Great Grandparents, 3rd cousins means shared 2xG Grandparents and so on. Everyone has 4 grandparents, 8 G Grandparents, 16 2xG grandparents, 32 3xG grandparents and 64 4xG Grandparents – however this would be different if you have cousin marriages in your tree). It’s estimated that everyone has approximately 4,700 5th cousins, that is a lot of cousins that you potentially could get DNA matches with. It’s most likely that your paper trail family tree has many gaps in it and that you have not documented your family at this level right out through all branches. After many years of research I know that I do not have all that information, and some information I do have is quite sketchy due to unavailable records and incorrect information. It’s believed that we all have 2 family trees. Our documented genealogical family tree and now our genetic biological family tree. Whilst these may be the same, there is definitely room for them to be different, with illegitimate births, unknown parentage, adoptions, and the like. DNA testing is bringing several family secrets out into the open. You need to be prepared that you may find out things that were previously hushed up.
- I immediately start a family tree with my match at the bottom of the tree – I use ancestry for this – I set up a new tree and make sure it is private (and also go the extra step to stop it being found in searches).
- Look through the profile of the match – can you find them on sites other than ancestry, can you find clues as to their parents or grandparents? Google their email address this often pops up with some ancestry type sites they have listed their details in. If in Ancestry you can search their member profile for any hint of a surname they might be searching for. In ancestry sometimes it says they have no tree, but if you look their is one they have just not linked to it. Google their name (if you can figure out their actual name) – or just google their profile name. You are looking for any hints (obituary pages, research pages, social media sites, 192 type sites etc) where they mention their full name or better yet parents/grandparents name. Fill in their tree with what you find. Sometimes you only need 1 generation in a tree to start finding more – especially if you are on Ancestry as you start to immediately get hints to build up the tree. Hopefully this leads straight to a common ancestor.
- Look at a “cluster” of people – those all matching on a particular chromosome and are confirmed to all match each other. If you can find a link to one, you should find them all fitting into place. I do this work all on my excel spreadsheet – but there are other tools to help you do this – two of the tools that spring to mind are GenomeMate and DNAGedcom. These sites have applications that help effectively manage your top matches and keep track of where and how they all match you and each other. I use a spreadsheet because I like excel and I use it a lot in my worklife, so I have built my own chromosome browser. You don’t have to do this (and you probably shouldn’t) – you can use sites that have applications already set up to use.
- Rule out where the common ancestor CANNOT be. This will stop you searching your entire tree to find a common ancestor. If you have someone marked down as a paternal match, then anyone matching that person should also be a paternal match (there will be exceptions and keep an eye out where one-to-one matches show something you weren’t expecting). Keep your family charts in front of you when doing this. There is an additional test here that can also help you – and that is the results from the X-Chromosome. The X Chromosome is 1 of the pairs of sex chromosomes that come from your parents – 1 from each. Your mother (regardless of your sex) will ALWAYS pass down her X-Chromosome (which will be a randomised version of her 2 X chromosomes from her parents) and your father will pass down an X Chromosome if you are a female and a Y Chromosome if a male). Although DNA inheritance on the X Chromosome is somewhat different than the other 22 pairs of autosomes, it can be used to try and rule out some areas of the family tree that the match CANNOT be on, given a male will not get an X match with his father. So if you are male and share matching DNA on the X Chromosome, you know that match cannot be on the paternal side and you share a common ancestor on your mothers side. GEDmatch does show X matches and the amount of DNA shared – you can use the X match information for this purpose, but be aware of trying to use for anything else. Due to the inheritance pattern of X DNA the match may have come many many years ago (before paper trail genealogy timeframes).
- Test more of your family – it really is helpful to have another family member to test, if possible your mother or father. Their matches will also go back 5-6 generations so this will give you additional matches another generation back. Testing the oldest living relative as soon as possible, should be on all of our ToDo lists!. There is limited use in testing a sibling, as they will be have similar matches to you (although some additional due to DNA inheritance – ie. they will have different bits of your parents). A relative who is paternal or maternal is definitely going to help you sort matches into paternal/maternal, once you can establish which side your match is from then it immediately removes 50% of your tree you need to search for the most recent common ancestor. However whilst you can sensibly conclude that anyone who does not match your mother MUST come from your fathers side, you can not make the same assumption with an uncle or aunt. They will have different bits of DNA from your grandparents than you do. You only have approximately 25% of their parents DNA and you cannot tell which percentage you have.
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