(A quick note, we’re using the newer version of GEDmatch called “Genesis” for this walkthrough. It’s soon to be the only GEDmatch, but if you’re not familiar with it, please use GEDmatch Genesis for this example.)

Back in our 1^st installment of this series (Link), we suggested that you upload your AncestryDNA results to GEDmatch. We’re hoping you’ve done that, and we’re going to walk you through why this site is so powerful.

GEDmatch is a private site that is run out of Florida, for the purpose of allowing genealogists to upload their tests from all commercial DNA providers, with a complete set of tools to help us make matches between different tests. The key to GEDmatch is both its great tools, as well as it being open and public with all of the tests that are uploaded, but that’s also the warning that goes with GEDmatch: your tests are searchable by anyone. Your raw data is never shared, but your match information is openly shared to anyone that joins, including law enforcement. There have been a lot of stories shared about how GEDmatch was used to solve nearly 30 cold cases (so far), and reunited 10,000 adopted children with their birth families. There is a real chance your uploading of your DNA data is going to unearth secrets that your family doesn’t want unearthed.

At first GEDmatch was bewildering and confusing to us…and most of the walk-throughs we saw online were so detailed, it only further confused us.

We’ll be honest, at first GEDmatch was bewildering and confusing to us…and most of the walk-throughs we saw online were so detailed, it only further confused us. So, we’re going to focus more on the functionality GEDmatch than the technical details. This is still rather advanced, but when you practice with your matches, and then search for the more the technical details, you’ll find it makes a lot more sense.

Each test uploaded to GEDmatch is assigned a kit number, and most of the tools will require you to enter either your or your target match’s kit number. Especially when you have multiple kits you’re working with, it will be helpful to have your main page with all of your kit #’s open while you work in other tabs. It’s easier to cut and paste.

One-to Many Comparison

On your home screen you will see all of your kits, and if you click a kit # you’ll be taken to the first tool: One-to-Many Comparison. When the first box comes up, to start with we suggest you filter on only those matches that are 20cM and up. A whole list of names and numbers will pop up, and this is the list of everyone who’s uploaded a kit to GEDmatch that matches your kit. Let’s walk through what each of the boxes mean:

Select – You can pick at least 3 kits here and shortcut several of the tools by clicking on the “Visualization Options” button on the top header.

Kit #, Name (Alias), Email – This the information for you match, including a REAL email address! No more sending an Ancestry message, never hearing anything, and wondering if they ever log into Ancestry. Some people (and we recommend this for everyone managing someone else’s kit) use an alias for their testers name.

GED/Wiki Tree – You can enter a GEDcom-format family tree, or a link to your WikiTree, to help your matches find that MCRA. We’ll walk through this later.

Age – How long has the kit been on GEDmatch

Type – The chip version your test was from. Ignore this, it won’t matter for what we’re doing

Sex – If the GEDmatch uploader didn’t select a Sex for their tester, this will be U

Haplogroup – Shows which group you’re line is in if you took a mtDNA (mothers) or YDNA (fathers) DNA test. Ancestry doesn’t offer these tests, and if there are values in this for your matches, ignore them for now.

Autosomal – This is the type of DNA test Ancestry offers, and it’s what you think of when you think of DNA tests (ie: 50/50 inheritance from mom and dad). This is the area we’ll most care about, and it lists the total cM’s you share with the match and the largest piece of match in your samples. The “Gen” value gives you an estimate of how many generations separate you and this match.

X-DNA – We won’t cover this much, although it will get at least a mention in later post. X-DNA won’t be of much value, except in one very specific way.

You can click the header of each column to sort the results, but in this case let’s take a look at one of the higher cM matches on my list that I don’t yet know who they are.

One-to-One Autosomal DNA Comparison

For our example we’re going to select kit #M717701, especially since they have a family tree shared for this match. Clicking on the “GED Wiki” link in the GED column opens a link to their public tree on wikitree.com, but reviewing all of the surnames there, I don’t see any that jump out at me. I’m going to copy the kit # and go back to the home screen, to check out our next tool: One-to-One Autosomal DNA Comparison

Here’s where you actually confirm your matches to other kits, and start to get a view into the actual DNA segments that all of these matches are built off of. In the Ancestry tool, you take their word for it that you match someone, but this tool will actually prove you’re related.

Entering our kit # first box, and pasting in M717701 in the second, we get a picture of exactly where we match, or if we actually share no significant DNA (it happens!). In this case, we match the sample on Chromosome 14, and the exact start/stop positions of the match are listed. (We’ll come back to that in our next post, about DNApainter).

If you scroll all the way down to the bottom there’s more detail about this match, the most important info showing the estimated number of hops to our Most Common Recent Ancestor (MCRA). In this example it shows as 4.4 between us and the GGP that we share, but it’s best to double that number and use it to estimate the number of people between you and your match. 4.4×2 is 8.8, so we’ll round up to 9, and when it comes time to build out the link between us we’ll expect that it’s likely 4 or 5 ancestors up to the MCRA, and 5 or 4 ancestors back down to the match. Without even going to the “Shared cM Project” graph, we can guess that it’s most likely the MCRA we’re looking for will be a 3xGGP (4 ancestors from me) or 4xGGP (5 ancestors from me). But, we need to narrow down which side of the family this match is on, which brings us to our next tool: People who match both, or 1 of 2 kits.

People who match both, or 1 of 2 kits

This tool is very powerful, and where we do most of our work, and make most our matches. This is especially true if you have more than one kit in GEDmatch, because you can quickly narrow down target matches to either being on your mother’s or father’s side of the family. For example, I have my mother’s and a paternal uncle’s kits uploaded, so if I use GEDmatch to show me all of the kits match my test and my target test, I can pretty quickly see if it’s on my mother’s side, or my father’s. Plus, I have many known matches that we don’t manage, so we can usually get pretty lucky on narrowing it down further.

For our example, we ran this test on our target user from above and we see that they match my mom’s test also, so we’re looking at a MCRA on her side. We just cut our search in half! Looking more closely, her cousins on her father’s side have maybe a dozen tests in GEDmatch, but none of them are listed here. It’s very likely then, given the volume and closeness of the paternal cousins’ tests that if this was on my mom’s father’s side, they would show up in this list…so we’re going to assume this match is on my mom’s mother’s side. We just took the total number of potential MCRA’s down in half again, so we’re really narrowing in! Given that we already have 21 of 32 5xGGP’s identified in that branch of the tree, odds are pretty good we’re going to find a common surname.

In this case, we’re going to have to do what we did in our last post (Link), which corresponds to DNA secret #2: we’ll spend most of our time building out other people’s trees! Looking at the GED Wiki tree they have up, there’s a decent 4 generation tree on the match’s father’s side, but only a mother’s name and birth/death. Since nothing on the father’s side jumps out, we’ll build out their mother’s side first.

The other huge advantage at this point with GEDmatch is that we have the direct email address of our relative immediately, and so, once we’ve validated we’re a match with the 1:1 tool, we can reach out to what’s likely their regular email account and see if they have more information.

DNA Triangulation

Triangulation is confirming that not only does your test match the target’s kit, but that another known ancestor’s kit matches as well. In the above example we confirmed I matched with the “One-to-One” tool, and we linked my mom with the “People who match both” tool, but technically we’re just guessing my mom’s kit also matches the target kit. I’ve never had it be wrong, but to really prove the match it would be best to confirm the matching segment for myself, my mom, and the target all match. There’s a GEDmatch “Tier1” tool for Triangulation (and we find it VERY worth it to donate $10/month to get the Tier1 tools!), but it’s just about as easy to do a One-to-One test between my mom and the target to do a full triangulation.

Going forward

Once we prove out the family tree link to our “Cake” ancestor, and we have our MCRA, we will have really narrowed down how we’re linked to everyone else on the “People who match both” list. There’s nearly 50 matches on that list that we now have very solid evidence on who the MCRA is. Even if we have to build out most of those trees manually, it’s likely we already have pieces of those trees built out when we made the first match.

That being said, it’s one of the reasons it’s so frustrating that Ancestry has such weak tools. If we could combine Ancestry’s strong base of Public Trees with GEDmatch’s tool set, our effectiveness when making DNA matches would be extraordinary! It’s also why it’s so important to upload/link a GEDCOM file to your GEDmatch tree. It doesn’t have a great interface, but even ugly tree’s make this search much, much easier!

Using just these 3 simple tools you can build out many matches using GEDmatch. Just keep practicing, and quickly it’s like you’ve been using it for years. And, as your skill in the tool grows, those overly technical online walk-throughs will help further unlock the power of AncestryDNA tests!

In our next installment, we’re going to use DNApainter to narrow down those matches were we have no data on how we’re connected to a verified match, so we know where to focus our traditional genealogical research, and we’ll talk about some of the more advanced topics we won’t dive into too deeply in this series.