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  • Writer's pictureAndy Lee

Find Your Most Common Ancestors from Different DNA Tests with GEDmatch

Quickly discover your most recent common ancestor from different DNA testing companies using GEDmatch. This will allow you to leverage the power of family trees and tests from 23andMe, MyHeritage, AncestryDNA, and Family Tree DNA process your DNA matches and see who is related to whom and how.

Finding the most recent common ancestor is the key to identifying how you're related to your DNA matches. GEDmatch has a tool called Define the MRCA from Your DNA Matches.

A Brief History of GEDCOMs on GEDmatch

GEDmatch really started as a GEDCOM comparison tool with the power of DNA added to it. It can help us find matches that using GEDCOMs that are linked together.

What are GEDCOMs?

Much like .XLS is the file format for Excel files and .DOC pertains to Microsoft Word Documents, GEDCOM is a file format used when exchanging genealogical data between different genealogy software. If you want to share genealogical data with other researchers who do not use the same software, then GEDCOM files ease that process.

By looking at the GEDCOMs using GEDmatch, we can find a most recent common ancestor leveraging the power of our DNA and shared family trees.

Introducing the GEDmatch MRCA Search Tool

Previously, you had to compare the family trees of other DNA Matches on GEDmatch to determine which ancestor you share in common. With this new genetic genealogy research tool, you can let GEDmatch analyze with the click of a few buttons.

If this sounds like the Ancestry ThruLines or the MyHeritage Theory of Relativity tools, you are correct. GEDmatch's advantage is you can find the common ancestor across DNA testing companies, rather than just test-takers from a single source.

To take advantage of the MCRA Tool, you first need to do the following steps:

  1. Save your BIOLOGICAL family tree from an online tree platform or genealogy software to a GEDCOM file format.

  2. Then upload the GEDCOM file to GEDmatch.

If you don't follow these two steps, you will not have any results as GEDmatch will have nothing to compare between you and your DNA matches.

For this tool to work, you AND your DNA matches must have uploaded family trees to the GEDmatch platform. If your DNA matches have not uploaded a family tree to GEDmatch, invite them to do so.

If everybody uploads a GEDCOM file to GEDmatch, we will all have lots of information to compare.

Link DNA to a person in the GEDCOM file

The next thing to do is link a person whose DNA has been tested to the GEDCOM file. This will usually be yourself or a close relative.

Key a DNA kit number for yourself or your relative that is on GEDmatch

screen shot of GEDmatch MRCA search tool

You'll see a few presets that you can use. You can change:

  • The number of kits that you're considering.

  • The minimum amount of centimorgans to be compared.

  • The match score.

Once you're ready, click on SUBMIT.

This process may take several minutes, so don't be worried when just one or two lines pop up.

Ultimately, GEDmatch will compare GEDCOM files to identify a potential most recent common ancestor. Let me say that again potential most recent common ancestors.

To see how to find your MRCA using GEDmatch, watch the video below.

Video: The GEDmatch Define the MRCA from Your DNA Matches Tool

A Review of the Potential Recent Common Ancestor

On the results page, you will see several things.

  • The kit number and the name of our match.

  • The number of centimorgans that is in that match, sorted from the largest down to the smallest.

  • The name in our GEDCOM kit of who that match is. Notice the name should be the same name or roughly the same name based on the matching algorithm.

  • How many generations away we are from that kit, and how far away our match is from that kit.

  • You'll then see a link to the actual path upwards and downwards through your MRCA to your DNA match.

Screenshot of potential MRCAs from GEDmatch

We can explore this further by going through each of these links and seeing what they're actually showing.

Previously I went over the different uses of the GEDCOM matching within GEDmatch. The information basically tells us who the parents are, who the spouses are, who the children are with some basic names and birthdates.

You can click on any one of these names to go to that person if you want to research that a little bit more. The link on this list really covers this primary person. It also covers what we would see from our matches GEDCOM file.

We can actually open both those up and compare them together to see if some of the information matches more directly or give us a clue as to whether or not this really is a most recent common ancestor.

Not all MRCAs are Accurate

In the video linked above, you pointed out that two matches are probably not the same person. My main clue is that the Jane Gordon that my grandfather is related to was born in Kentucky in the United States. Whereas GEDmatch found a Jane Gordon was born in Sutherland, and her descendants were all in New Zealand.

While it's still possible that GEDmatch found a match, it's more likely that other researchers or I have some errors in the research we have done. Or, it's possible this isn't the way we are related. Remember, a common ancestor tool can only compare information between trees and make recommendations based on similar data. You have to verify the suggestions.

The Confident Rating on GEDmatch

The Defined the MRCA from Your DNA Matches algorithm looks at many different things when comparing the family trees of DNA matches. These items include the name, the birthday, and the birthplaces. GEDmatch comes up with a score on how likely this is a most recent common ancestor or how likely these two people are the same.

A match score of 10 is a perfect score, while a 2 is relatively low. It's not surprising that a lower score turns out not to be a verifiable match. Keep improving the content in your GEDcom file, and hopefully, your DNA matches will do so as well.

Evaluate the results with the highest confidence rating first. Then work your way through the 2s and 3s.

↪️ Confused about DNA and genealogy?

Grab your copy of this FREE DNA guide:

DNA strand with the title Free Guide Answers to the Most Common DNA Questions asked by new genealogists

I hope this explanation of finding the most recent common ancestor with your DNA matches helps get you started in using this tool to really streamline some of your research. You can do this with some of the other tools on GEDmatch, but you have to sort through a lot of matches between two GEDCOM files. This tool makes it really easy.

Do you have any questions on using this tool, then put them in the comments below, and I'll try to answer them for you.

Plus, I also discuss a little bit about GEDCOM x files and the GEDmatch tool. It's a little bit too confusing for this blog post, but if you want to learn more about GEDCOM x, check out this interview.

More Tips on Using GEDmatch

Explore the following blog posts to continue your genetic genealogy education.

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