Find Most Recent Common Ancestor using GEDCOMs

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Finding the most recent common ancestor is the key to identifying how you are related to your DNA matches. And now GEDMatch has a tool that you can use to do that.

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Howdy, I’m Andy Lee with Family History Fanatics where we help you understand your DNA, climb your family tree and write your ancestor story along the way. Be sure to subscribe to our channel and if you’d like to become a member, you can join for just $2.99 cents a month for extra training throughout the month. Today we’re talking about a new tool at GEDmatch that is called the find the M R C A from your DNA matches. GEDmatch really started out as a GEDcoms comparison tool and with the power of DNA added to it, it can help us find matches that we should have GEDcoms that are linked together. By looking at the GEDcoms, we can find a most recent common ancestor. Now, previously you had to do this yourself by going through and searching through all the different matches where each GEDcoms matched in order to find a common ancestor.

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Well now you can do that with this new tool, but there’s a few things that you need to do beforehand. So one of the first things that you need to do is you need to make sure that you have a GEDcoms file uploaded to GEDmatch. If you don’t, there’s nothing to compare because this is not just looking at you and your DNA matches, but it’s also looking at your GEDcoms file compared to your DNA matches GEDcoms files. So if nobody uploads a GEDcoms file, then you’re not gonna be able to compare them. But if everybody uploads a GEDcoms file, then there’s gonna be lots of information to compare. So if you haven’t uploaded a GEDcoms file yet, then go ahead and do that now. Now the next thing that you’re going to want is you’re going to want to link a person whose DNA has been tested to the GEDcoms file.

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Now in this case it’s usually gonna be yourself or it may be a close relative, a parent or a grandparent if you have that DNA tested. By doing this, what we’ve done is we’ve created a definite link between a match and our GEDcoms file. So now the computer system can go through and it can try to match up where those GEDcoms files meet. So let’s go over to GEDmatch and see how this tool is going to work. So here is the tool and it’s going to be very simple. All we need is we need a kit number and I’m going to use my grandfather’s kit number for this because his is the one that I use most often in my research. Now there’s a few presets that you can use and right now we’re gonna start with just looking at this. With this all at what is preset, you can change the number of kits that you’re considering looking at.

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You can change the minimum amount of centimorgans to be comparing to, and you can change the match score. Now more on that in just a moment, but once you’re ready, click on submit and you’re going to start to see how some of these GEDcoms files might identify a most recent common ancestor. Now depending on how many matches you have that have GEDcoms files, this process may take several minutes. So don’t be worried when just one or two lines pop up and it’s taking a while for other things to pop up. The program is still working and it’s going to get there in just a moment. But this is the list of people that are potential, and I say that again, potential most recent common ancestors. So let’s go through this list and see what kind of information that we have. We start with the kit number and the name of our match.

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Next we have the amount of centimorgans that is in that match and this is all sorted from the largest down to the smallest. Next we have the name in our GEDcoms kit of who that match is. And you’ll notice that in our matches GEDcoms kit right here, it should be the same name or roughly the same name based on the matching algorithm. Then it also tells us how far away we are from that kit and it tells us how far away our match is from that kit, how many generations. Then there’s a link to the actual path upwards and downwards, and then there is the comparison of the two GEDcoms kits as well as a link to the GEDcoms and the person within that. So let’s explore this further by going through each of these links and seeing what they’re actually showing. I’m gonna start with our person.

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This is the person page for that most recent common ancestor that I would see in my GEDcoms file. Now there is another link there which is going to show it in the other person’s GEDcoms file. Previously I went over the different uses of the GEDcoms matching within GEDmatch and you can see that this information is basically telling us who the parents are, who the spouse is, who the children are with some basic names and birth dates, and you can click on any one of these names to be able to go to that person if you want to research that a little bit more. So that link really covers this primary person and it also covers what we would see from our matches GEDcoms file, and 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.

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So the next thing we want to do is we want to look at the descendency path to ourself, which also is going to be similar to this descendency path to our matches here. This link goes right to a descendancy path and it starts from the most recent common ancestor up at the top here, all the way down to whichever generation is going to be your match. In this case, it is Burton Lee, my grandfather. You can also see there that there is a little DNA symbol showing that yeah, that person does have DNA and if there was any of these other people in this list that had DNA also on them, then there would be that symbol as well. So these two links are going to this descendency chart. So that gives us the links to the Descendency path. And now we actually want to look at this path and this is actually probably one of the most useful parts of this tool.

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So on this descendancy path, what we have is we have the tendency to us and we have the descendancy to our match and they’re lined up by each generation so that you can actually see from the most recent common ancestor all the way down to you and your match, how that path goes. Now in this case, as I’m looking at this, I can actually see right off that these two are probably not the same person. My main clue is that this Jane Gordon that my grandfather is related to was born in Kentucky in the United States, whereas this Jane Gordon was born in Sutherland. And then also you can see the descendants were all in New Zealand. Now there it’s possible that these are the same person, if there is some errors in the research that either my match has done or that I have done, but based on what I already know, this is probably not going to be a most recent common ancestor.

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And where we can start to be looking is we can also be starting to look at this match score. What does this mean? Well, the algorithms looking at lots of different things as far as the name, the birth date, the birthplaces to come up with a score as to how likely this is a most recent common ancestor, or how likely these two people are the same people. In this case it’s a match score of two, and then we want a higher match score. A 10 is a perfect score, so a two is relatively low. So it’s not surprising that this one didn’t turn out to be a most recent common ancestor. So the path one is going to give us a nice side by side comparison of our pathway to our most recent common ancestor as well as the matches most recent common ancestor. But going back here, we can see on the score column here, we can actually use this to help investigate.

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And so for instance, I already said that this too is not going to be a most recent common ancestor in this case because it just doesn’t even match the right amount of information. On the other hand, when I’m looking down this list, I see hey, there’s this six right here, there is an eight right here. That’s probably a really good indication that they’re the same person and I’m seeing a lot more of these twos, twos maybe even some threes in that. And so each one of these, I’m going to want to be a little bit more skeptical as I’m looking at the twos to make sure that the information is exact or that the research is more correct rather than just assuming that this is the right person. But let’s go back and look at what the compare GEDcoms does. Now the compare GEDcoms just takes us over here to the compare GEDcoms tool where we put in our GEDcoms number and we put in the other GEDcom number.

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In this case it’s already been populated by the computer system. And then clicking on the compare, you can actually see all the people that match not just the most recent common ancestor, but all the people in this GEDcoms who match each other. So we’ve done the comparison of the GEDcoms and finally is the GEDcoms id, and this is just a link to that person in the file. So if I click on that, then I’m going to go over here and find this match. Now you’ll notice here on this match that they have their parents listed, they have who they’re married to and any children, and in this case they’ve been anonymized because these people are still living. But this also gives me links directly into that GEDcoms that I can see other people in that GEDcoms file. Now that I’ve gone through what each one of those links on this page does, let’s go and see what changing some of the default settings is going to do.

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Now in general, if you can take a look here I have 24 most recent common ancestor potentials down and I just want to emphasize that these are potentials you still need to go through and do research to verify or validate whether or not these are the correct most recent common ancestor with you in that match. So I have 24 and this comparison looks like it took about four minutes to actually run the whole thing. Going back to the start of the tool, I’m gonna actually change the minimum centimorgans up to 12 centimorgans. So the default is 7 centimorgans. So I’m gonna go up to 12 centimorgans take out all those matches that match less than 12 centimorgans, and here is the result. If we scroll down, we can see that hey, there’s a lot of the same people, although once we get down to the bottom, all those bottom ones are not there because this is only found 14 most recent common ancestors cuz it’s only looking for those that share at least 12 centimorgans or more.

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Likewise, you can see, hey, this only took 67 seconds, just a little over a minute in order to run because there’s a lot less information it’s trying to process. One of the other things that you can do is you can change the in a match score. Now GEDmatch actually recommends that you change us up to at least a three or greater in order to filter out any of those false matches. Now, I showed you an example already where I had a match that we matched 35 centimorgans, we had the same name, but from the birth date and the birthplace, it looks like this was not a most recent common ancestor and they only had a match score of two. So by doing with a match score of three or above, you’re going to limit the number of people that are shown, but these will be much more likely to be most recent common ancestors.

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In other words, the information that is shared in both GEDcoms files is much more similar. So here is my run, and this is with a minimum of 7 centimorgans, but a match score of three, you can see that the Jane Gordon is not the first one. It’s now this Jane May. And all of the twos that I had are gone. In fact, were down from 24 to just 18 of these are a grade three or higher. So this is one way that you can limit it if you end up having a lot of matches in this area. Now this is based on the number of your matches that have GEDcoms files attached to them. So as more people add GEDcoms information into the GEDmatch database, you are going to see more and more matches on this list. So I hope that explanation of the finding the most recent common ancestor with your DNA matches is helpful in getting you started in using this tool to really streamline some of your research.

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You can do this with some of the other tools on GEDmatch, but you have to sort through a lot of matches between two GEDcoms files. This tool makes it really easy so that you can just put in the GEDcoms file of your match. It’s going to search through all of the GEDcoms files of the other matches and identify the potential most recent common ancestor that can get you started on doing more research to verify whether or not that most recent common ancestor is the most recent common ancestor of you and your match. If you have any questions on how to use this tool, then put it in the comments below and I’ll try to answer it for you.