We promised to keep this series as science-free as possible, and instead focus on the practical use of AncestryDNA tests to identify your ancestors. We’re going to keep that promise here, but we want to say a few words about other types of DNA tests you can’t get from Ancestry, and how xDNA, yDNA, and mtDNA can be useful! Just remember, we’re generalizing a bit here, and if you want the detailed science behind all of this, Google has many great reads.
yDNA and mtDNA
yDNA and mtDNA come only from your father and your mother, respectively, and change very little over the generations. These tests are often written off in the genealogical community, because they won’t, by themselves, lead you to how you are matched with someone, or how many generations back you might match them.
For example, if our Michael has a yDNA test and he matches “Frank” who shares the same yDNA…it tells us next to nothing. From the test we know that on Michael’s paternal line we have proved he’s matched to Frank…but there’s no way to tell how. It could be 1000 years ago we all had a MRCA, or it could be that Frank’s 4xGGF was a brother to ours, but there’s no way that kind of range will narrow it down by itself.
There are two uses of yDNA and mtDNA, however, that makes these some of the most powerful tests you can take:
Geographical location
Unlike “ethnicity” estimates we see from all the major testers, yDNA and mtDNA can be very effective in pinpointing very accurately the location of your ancestors on the planet. The standard (Autosomal) DNA tests from Ancestry rely on a small global sample of historical DNA (16,000 samples currently), and human created Family Trees, to mathematically try and guess where our ancestors were 800-1000 years ago. They are looking for little shreds of DNA to trace back, and it’s very small amounts because Autosomal DNA gets cut in 1/2 for each side of a lin ever generation. However y/mtDNA doesn’t change over the generations and so we know very accurately where those ancestors were, based on where the bodies were found. This is especially important for African American genealogy, when there are nearly no records of origin before our ancestors were taken from Africa. These tests can be very accurate, and place your ancestral group in to very small physical and/or social (tribal) locations.
Brick wall research
In our example above, we know for a scientific fact that Michael and Frank share an MCRA along their paternal line. The same is true for women who have an mtDNA match. While that again doesn’t help us much if we have no information, it’s invaluable if we have a good guess on how we’re related. Let’s go back to our DNA Painter walkthrough to see how we wish we had yDNA and mtDNA tests.
To recap from last week’s post, we have two lines of DNA tests that we know are connected, and we have narrowed down the MCRA for both a cluster of AncestryDNA matches and on our line, but we don’t know how they connect. So, we have two couples (Jacob/Maria Kupsch, and Joseph/Dorothy Haasl) that we know match, most likely 2-3 generations above them. Each of them have 8 potential match relatives, and we have 4 known relatives, so we’re facing 32 ancestors that might be our MCRA.
But, if we can confirm the y/mtDNA from those 4 relatives, whom all died over 100 years ago, because that DNA doesn’t change between generations. That means a direct male relative from Jacob (say his son’s, son’s, son’s, son’s DNA) will confirm Jacob’s yDNA. Same for Maria, and a direct female relative. If we could yDNA test relatives of both Jacob and Joseph, and mtDNA for both Maria and Dorothy we would have about a 25% chance of finding an immediate match. And, if say Maria and Dorothy share the same mtDNA we just figured out we need to focus our research only on both of their maternal lines to make our match. If we don’t find that match, we just eliminated 25% of our potential match points, so now instead of building out 32 ancestors to find our match, we’re down to 24. But even better, if we can go one level up and do the same thing, we can eventually narrow this down to where we share an MCRA.
Here’s a great blog post that breaks this down a real-world example from Roberta Estes: (Mitochondrial DNA Bulldozes Brick Wall)
xDNA
Going back to the GEDmatch installment of this series (How to make the most of your AncestryDNA matches: Part 4 – How to quickly, and effectively, use GEDmatch), there was a column in our DNA matches that showed the amount of xDNA that we matched other testers. The good news is that all of the major test kits include xDNA measurements in their most basic test. The bad news is, it’s unlike the other types we’ve talked about, and it’s almost useless. With one very valuable exception.
It would be highly unlikely we could ever build out a family match with xDNA, and the cM you share with someone tells you almost nothing about close of a match you are with them. The main value of xDNA is if you do match someone, it narrows down your link to that match in a very powerful way. xDNA is inherited in a unique pattern that going back several generations can eliminate more than 50% of your tree as a potential match.
Women will inherit an X chromosome from both their mother and their father, but men will inherit an X from only their mother. Going back to High School Biology, we quickly remembered that women have an XX chromosome, while men have XY!
But, the value for us comes in when we build out our potential ancestor’s chart, using that inheritance pattern. So, if we have a female test subject who has an unknown xDNA match, we know it’s not from her Father’s Father’s line because men only inherit their X from their mothers. Going back 2 generations, we just eliminated 25% of the potential matches. If you know, from other research, that this unknown match is on their father’s line, you just confirmed it’s on the father’s mother’s line.
You won’t see a lot of xDNA matches, but when you do, Google one of the many xDNA inheritance fan charts, and start to see if you can eliminate suspects in how you match. It could bring you much closer to where to hunt for your MCRA.
Here’s a great break down of xDNA from DNA Explained, with more links to more detail as well: (Who Tests the X Chromosomes)
Just know that all of this work will have to be in GEDmatch however, since AncestryDNA doesn’t provide any information on the details of your genetic matches, and none of the tools needed to view/manage this information.
Just by going through that cluster, building out a central tree that links them all, we found a great lead that likely shows John’s arrival information, along with approximate birth years for Jacob, Mary, and John…as well as John’s previously unknown siblings who seem to have a long history together in the US, and left many records. That means instead of having exhausted all the on-site research we could do on the John’s line, we now have a large number of leads to follow and see if we can push back another generation from both Jacob and Mary. We now know enough to start targeting death certificates for both, which may contain critical names, as well as 6 more marriage/death certificates to look for Mary’s maiden name, as well pieces of evidence that link our Jacob to the arrival Jacob. And, DNA Painter has greatly narrowed down where we’re targeting our on-going research to finally break down this brick wall.
(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 
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.
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.
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.
As an example, let’s look at a match with an Unlinked Tree and 242 cM of shared DNA. Looking at the match’s Public Tree, the names don’t jump out (other than the very common “Smith”), but based on our notes, we know it’s on Michael’s Father’s Mother’s Mother’s Father’s line…which was William Arthur Smith. To confirm, we entered the cM in the DNA Painter Shared cM Project tool (
The next target is going to “A.G.”, a woman that shares 26cM with the same tester as the first example. The first thing we do is review A.G.’s shared matches with us, and we see notes indicating that the match is on our tester’s Father’s side, so we just narrowed our focus to that ½ of the tree. Next, we went to DNA Painter Shared cM Project tool and maped out the most likely matches for the level of shared cM, which shows that it’s likely our shared match is around a 4th Cousin, Once removed or a 5th Cousin. This means, it’s most likely we’re looking for 3x/4x GGP as our MRCA.
In the example to the left, our Most Recent Common Ancestor (MRCA) is our Great Grandparents, and Ancestry has mapped out each of the steps between us. Given AncestryDNA’s limited tool set, we only have a few ways to successfully build out our matches. The first of these was Hints, the next one we’ll use is “Notes”
When we click through to the test page, and select the unlinked tree, we find a dead-end: everyone is Private.
In GEDmatch we’d have a series of tools we could use to narrow down this match, but in AncestryDNA we can’t tell if this match is even Paternal vs. Maternal. But, if we go into the “Shared Matched” and look for any kits listed there that have a Note, we can click the note and see who they match. In this case, they match our Lila Miller match, which has the note we made before attached, so we know this match also is likely to be on Rick’s MMF’s line, and that they are also on Line 11. We will make the same note in this match, and return to our searching.