UPDATE 18-AUG-2019: Although many of the concepts in this post are good to know and the ethnicity calculators are not changed. The GEDMATCH site has had a facelist and hes been replaced by what was previously called the GENESIS site. So better to read the following posts:
If you and a relative have tested your DNA at different companies, you can compare your results at a free third party site – GEDmatch.com – which also has many additional, useful tools for analyzing your DNA and looking at match lists. Learning to use those tools may take some time as they are not intuitive, so I am writing this post to help a friend, Barbara, start to use them.
The GEDmatch site can be intimidating for the less computer savvy. Like most any place on the web, you have to register by creating a username (your email) and password . Click here for more details on registering in my GEDmatch Basics presentation starting on slide 2. Please do not be put off by the extensive new Terms of Service you have to agree to. GEDmatch has to meet the current EU requirements plus they need to warn you that your DNA could be used to identify a victim or catch a criminal among your relatives.
Once you have a username and password and log in, you are presented with a home page which, again, is not very user friendly. The first task, which we already did Barbara, is to upload your DNA test data. Start with this slide https://slides.com/kittycooper/gedmatch-10-13#/9 for the details of how to upload and manage your DNA results, known as kits, to GEDmatch.
The image to the left shows the big blue box, called “Analyze Your Data,” which you can find on the right side of your GEDmatch home page. I have put a red box line around the functions that I find the most useful. One of the first things I do for a newly uploaded kit is check if the parents are related (yours were not Barbara, nor Martin’s).
Once your kit is uploaded, it still has to be “tokenized” which you can think of as being put into chunks for the template they use for comparisons; this can take 24 hours or so. While you wait to be able to use your kit to look for matches, you can play with the ethnicity tools. Please remember that figuring out the groups you descend from is a science still in its infancy and far from accurate yet, other than in the broad strokes.
Start with Admixture (heritage). For most Europeans, the Eurogenes calculator is best and the default K13 is fine, but for those of us with mainly Northern European ancestors, K12 is better. I have a whole presentation on just these calculators at https://slides.com/kittycooper/gedmatch#/
Although its creator has disavowed the Eurogenes Jtest calculator for listing your Jewish percentage (click here for his article), I find that if you add up all the obvious ethnicities: Ashkenazi, Western_Med, Eastern_Med, West_Asian, and Middle_Eastern, it is not that far off. The Jtest image above is from Martin, the only person I have ever seen AncestryDNA call 100% European Jewish; most of my jewish friends come out between 87% and 98% there.
Click here for the creator, Davidski’s Eurogenes blog posts on Gedmatch. Two important take-aways for me are that his ancestral clusters are much further back than the main companies and any ethnicity of 1% or smaller is likely noise.
Once your kit has tokenized, you can start using the most important tool, the One-to-many compare function which will compare your kit to all the kits in the database and then list your closest DNA relatives.
One-to-many is the workhorse of DNA matching for us genealogists. When you click on those words in the blue box you get a form which lets you pick which of your kits to use or type in another one. There is also a default number for the largest segment which is set to 7. Change that to 20 if you are jewish, else to 10 or even 15.
Below is an image of your top One-to-many results, Barbara, with the first column (kit number) and last two columns (name or pseudonym then email) cut off for privacy. Note that the kit numbers start with a letter which tells you where they tested so A is Ancestry, T is Family Tree DNA, M is 23andMe, and H is MyHeritage. Warning, Ancestry kits will typically have more matching DNA with you here at GEDmatch, because Ancestry removes segments that it considers common in the population in their matching algorithm.
The red arrows added by me to the image are showing two important spots on the report. One is showing where you can click the underlined A to get a one-to-one comparison with that match. The one-to-one will show you exactly where you match, which chromosome and location.
Barbara, below is the one to one “position only” for your best match, *FT etc, who is clearly in the 3rd/4th cousin range.
None of the matches listed in the One-to-many above are close relatives as they share too few total cMs. All are about 4th cousins or so. Click here for the DNA Painter calculator which you can use to see the possible relationships for a specific total. However please remember that after second/third cousins, DNA inheritance gets more and more random and the total cM number cannot tell you the specific relationship, just the likely ones. I usually tell people to start with those people who share more than 100cM.
The second red arrow shows where to sort by largest segment which I often suggest to jewish friends that they do. Why? Because so many people will match you at a 4th cousin level who are really 6th cousins three times over or the like, due to much intermarriage (endogamy). Therefore we need the matching DNA segments to be large for those real 3rd and 4th cousins whose common ancestors might be findable. My recommendation is one segment greater then 20cM and another greater than 10cM and about 5 or 6 segments. That is just a guideline, not an absolute, but works well among jewish matches.
Start with this slide – https://slides.com/kittycooper/gedmatch-10-13#/25 – to see more about how to use the One-to-many function. Plus this blog post http://blog.kittycooper.com/2016/06/gedmatch-tools-2016/ explains the headings on the One-to-many report.
Some of your matches will have family trees posted. Read this post for more about that http://blog.kittycooper.com/2017/03/family-trees-are-now-linked-to-from-the-gedmatch-tier-1-one-to-many/.
My recommendation is to contact just your best matches at first. If you have other family members tested and so know which line the match is related on because of who they match, tell them! Be specific in your email as to where your family lines are from and include a link to your tree. Best is to add your tree to the collaborative world tree at WIKItree then add your GEDmatch kit number to your profile there with a public biography and tree (dates are still private for the living). If you do all that, a link to your tree will appear next to your kit number in your matches One-to-many. Alternately, you can upload your tree to GEDmatch itself which also puts a link next to your kit number, but be sure to privatize it first.
There are many advanced GEDmatch posts on this blog. They are listed on the DNA advanced menu under Gedmatch posts for your further reading, eventually.
One problem is that newer DNA tests like 23andme since August 2017 or LivingDNA can only be uploaded to GEDmatch’s in progress site: Genesis, because the underlying chip for these DNA tests is different from the previous kits used. My screen shots are not accurate for Genesis but the concepts are. I look forward to this post being outdated very soon when the conversion to that site is complete. If you have kits at GEDmatch they are automatically being migrated to Genesis and your same login will work there.
Have fun Barbara!