double cousin
n.— «The couple celebrates with both families at once, since Zeba Shah’s husband’s brother is married to her sister.…Children conceived from such unions, often called “double cousins” because they’re first cousins twice over, are genetically more similar than cousins, but share fewer genes than siblings. They also have the same two sets of grandparents.» —“Families’ double bonds” by Alexis Grant Houston Chronicle (Texas) Dec. 24, 2006. (source: Double-Tongued Dictionary)
My mother’s Swiss immigrant family in Nebraska used this term at least as far back as her young adulthood in the 1930’s. In the last few decades of the 19th century, marriages were encouraged to take place within the same language- and- church group, and the combination of sparse populations on the prairie and large immigrant families often encouraged pairs or even trios of siblings to marry.
I am a double cousin, which I love being. It is really great to have exactly the same relatives all the way around… Thanks Linda Lang