In my last post, I briefly explained how I think you can use Y-DNA to show that all Mennonite Fasts in West Prussia are likely descended from a fairly recent ancestor.
But the situation is a little different for my maternal lines, the Siemens. If you look at the table of Mennonite Y-DNA and surnames maintained by Glenn Penner, you can see how the Mennonite surnames break down into groups. For instance, if you scroll down to the Siemens, you can see that Glenn has broken them up into two groups, separated by the bold line. The first four men tested share virtually the same Y chromosome, while the second five men do as well. But the first and second groups are different from each other. The columns on the right are the number of times certain sequences of DNA molecules repeat. Here's a snip from the spreadsheet:
I had my uncle, my mom's brother, tested before he passed away; and his Y-DNA matched the first group. If I would research the ancestries of those three men, they should converge at some point, perhaps in the 1600s. It also means that there is no point trying to connect to the ancestries of the Siemens men in the second group.
When I checked in Grandma, I found that the man on the third line, Jacob Siemens #2169, was born in Alt-Muensterberg in 1764, which is the same village in which my 4-greats-grandfather Klaas Johann Siemens #46557 was married in 1787. That would make them of about the same generation.
I haven't started on this project yet because I am working on connecting Fasts in the 1776 census. But once I finish with the Fasts, I will take up this group of Siemens and see where it leads.
BTW, I have had no success using the list of matches at FTDNA for my Y-DNA. Out of the hundred or more matches for each of my two surnames tested, Fast and Siemens, I have had only one match with a Fast surname and none with a Siemens surname. I think this is because both these lines are of Dutch and Flemish origin, and the Dutch only took surnames late in history. It's much better to use the Mennonite Y-DNA table that Glenn Penner has put together.