My participation in tonight's Saturday Night Genealogy Fun challenge from Randy Seaver is not going to be pretty. Or fun.
Come on, everybody, join in and accept the mission and execute it with precision.
1. How many autosomal DNA matches do you have descended from your eight 2nd-great-grandparents (they would be your third cousins)? Do you know how they are related to you? Have you corresponded with them? Why are your numbers high or low?
2. Share the number of your autosomal DNA matches for each of your 2GGP and answer my questions above on your own blog, on Facebook or other social media, or in a comment on this blog. Share the link to your post on this blog, so readers can respond.
Oh, this is going to be painful.
First, I need to mention a couple of clarifications.
I do not have eight 2nd-great-grandparents. I have sixteen 2nd-great-grandparents, as does everyone else. I have eight pairs of 2nd-great-grandparents, which I'm pretty sure is what Randy meant (and what I changed the title of mine to).
And not all of my autosomal matches who descend from any given pair of 2nd-great-grandparents are going to be my 3rd cousins. I can have other relatives in addition to 3rd cousins who descend from one pair of ancestors. If the question was intended to be "How many autosomal matches do I have who are identified as 3rd cousins?", that's significantly different from what Randy wrote, and he wouldn't have to ask, "Do you know how they are related to you?" Maybe he started with one idea and it morphed into another.
Now that I've cleared the air on that (once an editor, always an editor), on to the disaster of my response for this challenge.
I have mentioned before (particularly when the question of DNA comes up) that my mother was Ashkenazi Jewish and that Ashkenazi Jews suffer from high degrees of endogamy due to lots of intermarriage.
Well, on Family Tree DNA, my current results show that I have 24,697 autosomal matches.
I'm sure that the vast majority of those are on my maternal side, and I have no idea (and probably never will) how they are specifically related to me, due to endogamy and the lovely obstacles that can exist for doing Jewish research in the former Russian Empire in general, particularly in the former Grodno guberniya, where three of my lines go back to.
For reasons unknown to me — I have not actually done much with my FTDNA matches in quite a while and have not kept up with all of the announcements — 1,525 of those matches are identified as paternal, 38 as maternal, and 710 as both.
I have very few matches on FTDNA where I have identified the specific relationship I have with them. So I have no idea how FTDNA has come up with the numbers of matches that are paternal, maternal, or both. I'm pretty sure I have not identified 38 relationship matches total, much less 38 on my maternal line alone.
And there is absolutely no crossover in a genealogically relevant period of time between the paternal and maternal sides of my family. Absolutely none. Period, end of report.
So I have no idea how FTDNA has identified 710 of my matches as being both paternal and maternal. That is just flat-out wrong. Unless there is another way to interpret "paternal and maternal" that I'm not coming up with on my own.
On top of all that, I don't even know one set of my 2nd-great-grandparents, because I as yet have not identified the biological father of my paternal grandfather. If I don't know who that great-grandfather was, I don't know who his parents were.
As for the number of matches I have who are descended from my eight sets of 2nd-great-grandparents?
To quote Randy:
The number of autosomal DNA matches I have on FTDNA with a known common 2nd-great-grandparent is:
NONE.
The number of autosomal DNA matches I have on AncestryDNA with a known common 2nd-great-grandparent is:
Three total.
• James Gauntt (1831–1899) and Amelia Gibson (1831–1908): 2
• Mendel Hertz Brainin (c. 1860–1930) and Ruchel Dwojre Jaffe (c. 1866–1934): 1
Some days it's just not worth chewing through the straps.
I do have additional cousins who descend from various of my 2nd-great-grandparents and for whom I know the exact relationship who appear as autosomal matches in both databases. I have corresponded with almost all of them. Several of them I was able to determine the exact relationship only because I corresponded with them. Some I recognized by name and knew the relationship immediately.
The huge numbers of matches on my maternal side I already discussed above. I don't really know that I would characterize the numbers of matches on my paternal side as being particularly low. It's more that I don't know the exact relationship for most of them. That is due mostly to a lack of response when I have reached out, particularly with matches on AncestryDNA. I attribute that to the fact that many, many people who test at Ancestry do it strictly for the cutesie-poo (and mostly useless) pie chart and don't care about anything else.