Saturday, February 17, 2018

Inheriting atDNA from 3rd Great-grandparents

Recently I have transferred to or tested about three dozen extended family members at MyHeritage. The recent upgrading of the tools by MyHeritage has moved the company's DNA services into the 21st century. If you haven't taken a look in the last month, you owe it to yourself to do so.

About a week ago I discovered a match from Germany for the maternal grandmother of my three Dowell grandsons. 

Those of you who are perceptive genetic genealogists will recognize that this amount of shared atDNA is well within the bullseye of what 2nd cousins would be expected to share. It also could be on the fringe of what could be expected if the two were one generation removed from each other within their families.

Particularly since my in law had been born in Germany, this appeared to be a match well worth pursuing. My interest was intensified when I discovered that "Weirauch" was one of the family surnames listed by the match.

Looking farther down the match list, I found my daughter-in-law:
She matched her mother as a daughter and shared a little less than half the atDNA her mother did. This would be about what we would expect because she was a generation farther removed from the matched individual.

Continuing down the match list I discovered my three Dowell grandsons. They were listed based on the amount of atDNA they shared with their maternal grandmother since it was her account I was using for this investigation. Those of you who read my blog posts a few months ago about how each of my grandsons inherited their atDNA from each of their four grandparents will not be surprised that MyHeritage reported their match with her ranged from almost 35% down to just over 23%. 

The boys are second cousins -- twice removed since the match is a second cousin of their grandmother. As such they would be expected to share about as much atDNA as third cousins and they do. However, I was surprised to find that the grandson who shared the most atDNA with his maternal grandmother, shared the least of the three with her second cousin. This is one more example to remind us of the random nature of atDNA inheritance. I guess I should learn not to assume predictability and just observe the data. 

Yes, this did turn out to be grandma's second cousin with whom communications had been lost when part of the family immigrated to America. A reunion is in the works that will include the grandparents, the parents and the grandsons during their spring school holiday in a few weeks. 

The source of the matching at DNA:

The connection of my grandsons with their newly discovered second cousin --twice removed is through a common descent from Max Weiranch (1878-1923) and Paulene Mittman (1878-1934) who were both born and died in Brieg, Schlesien. Max and Paulene were the boy's 3rd great-grandparents and between them they made a contribution that lives on in each of the boy's atDNA.


Each grandson inherited an identifiable and similar but different pattern of atDNA from this set of 3rd great-grandparents.