An example of endogamy in my family

Last updated September 5th, 2023

After a thorough research at the archives it turned out that my grandmother and her second cousins share 6 out of 8 great grandparents! This is called endogamy. One generation further, my grandmother’s cousins encounter what is called pedigree collapse as Johann Martin Meier and Anna Elisabetha Wolf appear twice in the family tree.

The known ancestors of my maternal grandmother, Elisabetha Antoni, have all different family names. For this reason, I was not thinking much about endogamy in my family until recently, when the results of two of my grandmother’s second cousins came in.

The idea behind testing V.A. and E.A.S. was the hope to map additional DNA segments to the line of my great grandfather Heinrich Antoni. To my surprise, however, the amount of shared DNA was unusually high for a relationship this distant.

According to the Bettinger table the average amount of shared DNA for a 2C1R is 123cM and 74cM for a 2C2R.

However, the results of my family looked like this:

What was going on here?

After telling my family about the results, my mother remembered that Klemens’ older brother was a very close friend of both of my great grandparents, Ottilia Arnhold and Heinrich Antoni, because he was a first cousin to both on different sides. I contacted other family members, who confirmed the story, and learned that the name of Klemens’ mother was Sophia Arnhold.

That seemed to explain the higher amount of shared DNA, and even though it still seemed a bit too high, I thought it was due to the randomness of DNA inheritance typical for such a distant relationship.

But then I noticed that V.A. was also matching K.M.Q., one of my American cousins on Ancestry. (E.A.S. tested at 23andme and could not be compared directly to K.M.Q.)

That was not supposed to be the case. A while ago K.M.Q. and I found our common ancestor quite quickly – which was remarkable, because that ancestor was a MILLER. According to a marriage record, Simon Miller and Rosa Louis were the parents of my great great grandmother Sophia Miller. According to the documents K.M.Q. received from her uncle (and also forwarded to me) her line can be traced back to Simon and Rosa as well. Their son Johann (John) Simon Miller emigrated to the United States and was the great grandfather of K.M.Q.

I just learned that the Antoni sisters were also related to my great great grandfather Johannes Arnhold. And now also to his wife? And if yes, then how?

Then a light bulb went on. I wasn’t really interested in V.A.’s and E.A.S.’s maternal side of the family before, because I always assumed our relation was through their paternal side only. I asked what the maiden name of their mother was and got “Anna Miller” as an answer. Everything made perfect sense now! I quickly checked our family tree to see how many brothers my great great grandmother Sophia Miller had. Apart from John Simon, there were also Matthias and Raimund. I then asked about Anna Miller’s patronymic. “Anna Raimundovna” was the answer…

So that’s what it was! V.A. and E.A.S. are related to our family through three different lines instead of one. Their father Klemens was a first cousin to my great grandmother Ottilia Arnhold and her husband Heinrich Antoni. In addition, Ottilia was a first cousin of his wife Anna Miller.

That makes it more difficult to assign the DNA segments my family shares with the Antoni sisters to a single line, because it is a mixture of Antoni, Arnhold and Miller segments. (After visually phasing my mother’s chromosomes and those of her siblings, I was able to assign these DNA to the right family lines after all.)

The colonies on the banks of the Volga river were close-knit communities, where intermarriage within the colony or between befriended families often took place. The idea behind it was to strengthen the family bond. It seems to have mattered though that bride and groom were themselves not related (at least not closely) the way it was the case with Klemens and Anna and also my great grandparents. However, they still married into the same families, so that their descendants are linked in many ways today.