Tag Archive | GEDmatch Tools

Using GEDmatch to see where you match

Oct3

I think the switch from Ancestry.com DNA test results, where your tree gets searched for you, making using DNA with genealogy easy – to GEDmatch where you have to figure out how to use the data yourself, is quite difficult. So this post is an attempt to help my cousins who have tested at ancestry and uploaded to GEDmatch. It might also help others new to GEDmatch who want to look at where they match a [possible] cousin by walking through that process.

GEDmatch Sample One to One

Sample from the GEDmatch one-to-one comparison

  • First make sure that you understand current DNA basics (click here for my page on that). Genetics have advanced greatly since my high school biology class and perhaps since yours too.
  • Next realize that the raw data from your test is only a small part of your genome, a sampling. It is the SNPs that are currently considered the most interesting. They represent the most likely spots where we are different from each other. If a contiguous sequence of those SNPs is the same in two people for about 10 centimorgans (cMs) or more then they are expected to share a common ancestor. With a match of 7-10 cMs it is likely but not a sure thing. There is a good article in the ISOGG wiki on the likelihood of a match at different segment sizes.
  • In order to see where your DNA matches someone else’s, you need your kit number and his kit number. Then you can use the one-to-one comparison to see on which chromosome(s) you match each other. Your kit number shows on your GEDmatch homepage. You can find the kit numbers of other possible relatives in the one-to-many display or perhaps your new cousin has sent you his kit number.
  • I recommend that you keep a spreadsheet with the information on your matches, sorted by chromosome and start point, so you can see who else a new match might match. I have a number of posts on this blog about using spreadsheets and a template in my downloads area. Many people like to use the genomemate tool to organize their data.

The image above is from a recent new match to my Dad uploaded from ancestry.com. The blue rectangle shows where there is a DNA match. The numbers in the box are what I cut and paste into my master spreadsheet for Dad.

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The GEDmatch Chromosome Browser (for my cousins with ancestry.com kits)

Sep22

Most of my matches at ancestry don’t see why they should upload their data to GEDmatch. I send them the URL of my slide presentation and extol the delights of the fun ancestry composition (admix) tools but it is hard to explain why I like to see where my DNA matches someone else’s. Curiosity? It’s fun? I love making these spreadsheets? Possibly it is because I am very interested in how DNA inheritance works and love to see which grandparent gave me which piece of DNA (n.b. it takes a lot of work to get to that point).

MyGEDmatchSlidesWhen I know the common ancestor for a specific segment sometimes a new match fits in immediately to a family line. The best example of that is finding my previously unknown 3rd cousin Katy. When I saw where she overlapped I emailed her that it looked like she was related on my WOLD line to which she responded that her grandmother was a Wold. She has since sent me many wonderful family pictures that I had not seen before.

Today I got an email from someone who had tested at ancestry and uploaded to GEDmatch. She wanted to know how to use my tools with her GEDmatch data. However my tools require a CSV file of overlapping segment data which cannot be downloaded in one fell swoop from GEDmatch, unlike at 23andme or Family Tree DNA.

Personally I built my many CSV files (one per person tested) slowly, as I compared each individual’s DNA results, contacted that match, and then cut and pasted the overlap information into my spreadsheets. Jim Bartlett did a great guest blog here on the process of building these DNA spreadsheets.

But I can understand the desire to see a quick picture of your matching DNA. GEDmatch does have a chromosome browser where you can see the overlaps, although the presentation is somewhat different from other sites. A little known secret is that you can massage that function’s table output into a spreadsheet (see end of this post for the technique).

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What to do at the GEDmatch site

Dec4

A DNA cousin who just uploaded his ftDNA results to GEDmatch asked me what he could do with them, so I decided to write a blog post to answer this question. Here are my favorite things to do there:

  • make pretty pictures of your populations ancestry – called the Ad-Mix page
     (see more on that below)
  • get a list of possible relatives who have tested with other companies as well as the one you tested with, that is the “One to Many” option on your home page. Email addresses are shown but you cannot just click on them, you can cut and paste the first part but then you have to retype the ISP  (prevents spam)
  • look at a specific area of one chromosome to see who else matches you there – “Find people who match
    with you on a specified segment”
  • compare your GEDcom to one other to see of you can find that elusive MRCA
  • compare your GEDcom to all your DNA matches that have uploaded GEDCOM files

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Phasing: or how to look at what you inherited from one parent only

Nov5

So in the images in my last post about GEDmatch you may have noticed that my Dad has less Mediterranean, Siberian, and Southwest Asian than I did. Perhaps you are wondering if there is a way to see what I got from my mother? Separating what you got from which parent is called phasing and you need to have at least one parent tested and uploaded to use this function at GEDmatch. The Genetic Genealogist has a good explanation of phasing in this blog post – http://www.thegeneticgenealogist.com/2012/06/07/gedmatch-com-adds-phasing-tool/

Here is what I got from my mother although GEDmatch cautions that the phased data may not be all that accurate.

 

 

Eurogenes 12b does not have as many Northern breakouts but does include Finnish which is of interest since Dad has several Finnish matches so I collected all the Finnish percentages. As you can see Mom had some too and Shipley got more than I did:

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GEDmatch: a wonderful tool

Nov5

One of the best tools around for genetic genealogy is the GEDmatch site which allows you to upload your raw data from whatever service you used and compare it to everyone’s data at GEDmatch in many different ways. But my favorite tool is the pretty pictures of your ancestry mixtures (called admixtures). Here is mine using the Eurogenes K12 calculator which seems best for us Northern/Scandinavian folk:

 



What does it all mean? A discussion of these populations is here at the Eurogenes blog.

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