Gedmatch 101

Whenever I’m working on a DNA project for genealogy, I likely spend some time on Gedmatch.  Here’s a primer for those unfamiliar with Gedmatch for what it is and what it can do.

Gedmatch is a very powerful 3rd-party tool that anyone who has DNA-tested at a major DNA site (AncestryDNA, 23andme, FamilyTreeDNA, MyHeritageDNA or LivingDNA) can utilize.  While much of Gedmatch is free to use, including uploading and finding matches, advanced features are available with a premium membership of $10 a month.

The fact you can take your DNA results from one site – for example, Ancestry – and unlock new matches from other DNA sites – 23andme, FamilyTreeDNA, etc. – is reason alone to upload.  More matches equals more potential to expand your family tree, learn more about your family history and break down brickwalls.

But it’s great to upload for other reasons too.  If you’re interested in mapping your DNA to different families, with DNA Painter or Genome Mate Pro, you’ll need segment data and known cousins.  Gedmatch provides segment data for your matches that isn’t provided on Ancestry, for example.  You might also help adoptees find their biological family, a major use of Gedmatch.

To get into the Gedmatch database, you need to first download your raw DNA data from your testing company.  You can then upload it to Gedmatch.

AncestryDNA

  • Go to Settings, then Download Raw DNA. Click Download Raw DNA.
  • It emails you to confirm and then you can Download.
  • It saves to your computer.

23andme

  • Click the top right of the page and go to Browse Raw Data.
  • Click Download.
  • Go to Submit Request, it will email you and then you can save the raw data.

FamilyTreeDNA

  • Hover over myDNA at the top of the site, then Family Finder, and click Download Raw DNA.
  • Click Build 37 Concatenated Raw Data, and it will download.

One thing you’ll want to think about as you upload to Gedmatch – should you use your real name?  You don’t have to. You can use an alias or nickname if you like.  Some people prefer to use their real name, but it’s totally up to you.

When you upload, you’ll be asked, do you want law enforcement to be able to compare DNA that they have access to, such as at crime scenes, to your DNA?  You have to explicitly “opt in” for this.  It can help solve cases and it’s encouraged you opt in, but it’s your call.

It’s free, it takes 5-10 minutes, and you’re sure to learn some new things along the way.  The first time a distant relative asked me to upload to Gedmatch, I was skeptical, as I hadn’t heard of it.  But after doing significant research on it, and now having used Gedmatch for about 3 years to help with my research, it’s great to have it in the toolkit.

In addition to new matches I wouldn’t have found otherwise, Gedmatch’s best use is comparing segment data. For example, here is how I matched a known cousin on Chromosome 22:

An example of segment data in a one-to-one comparison, as provided by Gedmatch.

The blue line shows the DNA that we share on that chromosome. After significant research on this segment, finding several others who matched here (triangulation) and through visual phasing, I learned that this segment was passed down from my 4th great-grandfather, who was born in Ireland. I descend of one of his daughters, and this match descends of one of his sons. Other descendants of this ancestor also inherited this same segment.

So, in time, Gedmatch helps you determine which segments of your DNA you inherited from which ancestors.

You have access to this one-to-one comparison functionality immediately after uploading. Your “one-to-many” matches – all of your matches – take about 24 hours to process.

Another thing you can do on Gedmatch is run a “People who match both kits” search. I can put in a match’s Kit # and my Kit #, and run a search, and it will show the other kits on Gedmatch who match us both. That could mean that we all have common ancestors. It could also signify endogamy or randomness that we all match by chance. No matter the case, this is sort of the equivalent of Ancestry’s “Shared Matches,” especially those who share more centimorgans with both kits (20+ is great). It can be really useful to figure out matches you’re unsure about.

matching-segment-search-in-gedmatch
Matching Segment Search

Finally, one of my go-to tools on Gedmatch is the Multi-Kit Analysis. This allows you to compare as many as 100(!) kits against each other, as long as you have the Kit #s. I usually only compare 5-10 kits together at a time, and sometimes if I’m focused on a specific family, I may look at 30-40 kits together if I know they’re connected to that family. Among the things you can do here, you can see all of the segments you share with the kits you chose (Matching Segment Search), you can run an autosomal matrix to see who matches who and for how much DNA, and you can do some other advanced analysis.

Gedmatch can do a lot more too, but these are some of the most useful features. If you’re interested in mapping out your DNA, taking down a brick wall, or extending your family tree, Gedmatch is absolutely key to have in the toolkit.

Looking to take your DNA to the next level? Have a look at these great books:

(The above links are affiliate links, which means we may receive a small commission from your purchase at no extra cost to you. Thank you for supporting Irish DNA Net!)

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s