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Old 04-28-2018, 04:58 PM
 
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On my paternal side, my grandmothers were sisters and my grandfathers were brothers. In other words, my grandfather and his brother married my grandmother and her sister. One of the couples had a son (my father, Stan) and the other couple had a daughter (Stan's double cousin, Doris). Stan and Doris married brother (Glen) and his sister (Jane, my mother)--Stan and Jane, Glen and Doris. What is the genetic relationship between a child of Glen and Doris and a child of Stan and Jane?
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Old 04-28-2018, 06:18 PM
 
Location: Colorado (PA at heart)
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Originally Posted by Jeanette1230 View Post
On my paternal side, my grandmothers were sisters and my grandfathers were brothers. In other words, my grandfather and his brother married my grandmother and her sister. One of the couples had a son (my father, Stan) and the other couple had a daughter (Stan's double cousin, Doris). Stan and Doris married brother (Glen) and his sister (Jane, my mother)--Stan and Jane, Glen and Doris. What is the genetic relationship between a child of Glen and Doris and a child of Stan and Jane?
So double cousins from one family married siblings of another? I don't think there's a name for that, because there's no name for the children of double cousins, they're just 2nd cousins with a little more endogamy. So the children are simply 1st cousins on one side, and 2nd cousins (of double cousins) on the other. The children of double cousins will have more shared DNA than normal 2nd cousins, and obviously they will share more than normal 1st cousins since they shared ancestry on both sides.

Normal 1st cousins share about 12.5% of their DNA. Normal 2nd cousins share about 3.125% of their DNA but with their parents being double cousins I guess they'd share more like 6.25%. So theoretically they would share about 18.75% of their DNA. Of course, since recombination is random and the actual amount of DNA cousins of the same degree share ranges, it could be anything from around 11% to 27.5%.
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Old 04-30-2018, 07:50 AM
 
Location: Arizona
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Originally Posted by Jeanette1230 View Post
On my paternal side, my grandmothers were sisters and my grandfathers were brothers.
Your father can't have 2 mothers and 2 fathers.
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Old 04-30-2018, 10:34 AM
 
Location: Colorado (PA at heart)
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Originally Posted by thinkalot View Post
Your father can't have 2 mothers and 2 fathers.
She's talking about double cousins - when two siblings from one family marry siblings from another family. Their children are double cousins.

https://en.wikipedia.org/wiki/Cousin#Additional_terms
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