The tools at each DNA web site are different than the others, but the end goal is the same: connection with cousins. Ancestry is missing a key tool that can be found at GedMatch and at Family Tree DNA (FTDNA). That tool is the chromosome browser or chromosome comparison.
I was contacted by a gentleman that I'll call John. He is in my match list both at GedMatch and at FTDNA and he's been working with DNA for quite a while. I have part of my tree available at FTDNA and he had checked it out. His family and mine had intermarried in Weakley County, Tennessee, during the late 1800s. We don't see a common ancestor yet, though we know we must have one. But what does our DNA tell us?
Looking at GedMatch, he's near the top of my match list with an estimate of 4.2 generations to our common ancestor. His kit number is on the left and his email on the right. I've hidden both of those items. He and I don't have any X-chromosome (#23) DNA in common. But our Autosomal DNA (#1-22) has a fairly large matching area.
Let's do a chromosome review at both GedMatch and FTDNA.
GedMatch shows us, in blue, several areas where we have matches within different chromosomes. It's larger on the screen. This is just small so I can show more of the matching areas.
Here's the FTDNA match list, where John is the second one. He has an email address, a tree at FTDNA and I can add a note. Some of his his surnames are shown and I can also see which DNA tests he has done.
In the chromosome browser, I select John (in orange). This browser shows only the larger match. I was able to find several other people in my match list with a very similar matching pattern. The gray areas are not used in matching. At the top, I can download the matches to Excel so I can see the numbers.
OK, we have matching DNA. So what? My first question to John was what he knew about the source of that section of shared DNA.
John has worked with several of those matches over the past few months and they can't find the common ancestor. I'm new to the game, but I bring some new surnames to explore. We have a location to focus on, which John said they didn't have before. I also knew more about my family than John did and he taught me things about his family. Together, we have a clearer picture of how our families relate.
If John and I can find our common ancestor, everyone who matches us on that piece of DNA will suddenly know what they are looking for. We'll be able to say that segment came from our ancestor X. Anyone who matches that location in the future can be advised to look for their connection to ancestor X and their parents and siblings. Others may be able to help refine the source of the DNA as the mother of X or father of X.
The chromosome browsers are interesting, but useless by themselves. The payoff is when you find the connection to that common ancestor X.
What's the strategy? Work the closest matches first. Review trees. Send emails. Ask if they know about the common ancestor in the DNA segments where you match. When you find the common ancestor, document the DNA segments and look for others that match those segments. Then reach out to those others to let them know what you've found. And, of course, hope others will let you know when they unpuzzle a match.
I sent such an email the other day. I searched on a particular surname, found a match, found the common ancestor couple in his tree, then used the chromosome browser. I looked for others with a matching segment and emailed a woman to share what I found. I now have a list of 8 DNA segments that associate to two surnames. The largest is on chromosome 22 from 41311622 to 44012037. It's up to me to keep track of those numbers and the associated surnames. I'm looking for a way to do it, but Excel is what I'm using for now.
I hope that example is simple enough to follow. Let me know.
No comments:
Post a Comment