April 13, 2006

Double cousins?

I am not an expert in kinship vocabulary, even in my native language, and the other day I found myself wondering whether either English or Spanish had a word or short phrase for a concept that arises in connection with my sister-in-law and her cousin. Is there a term for a cousin whose father is the brother of your father and whose mother is the sister of your mother (or perhaps, whose father is the brother of your mother and whose mother is the sister of your father)?

This arose when Barbara and I recently spent some time together with my brother Richard and his wife Amparo at an apartment in Spain borrowed from Amparo's cousin Begonia. (Hence my two-week absence from Language Log Plaza.) Richard and Amparo were indulgent to me as they drove me around some of Spain's stunning grandeur and I slept off my jetlag in the back seat of their car, and then after a few days plugged in my laptop in and worked on a paper I had to give in England at the (very enjoyable) DELS conference. We learned while we were there that Begonia is Amparo's cousin twice. Amparo's father's brother is Begonia's father; but if he had not been, Begonia would still have been Amparo's cousin, because Amparo's mother's sister is Begonia's mother, and either of those connections would suffice for cousinhood. So what happened was that two brothers chose as wives a pair of sisters; Amparo is a daughter from one marriage in such a pair of marriages, and Begonia is a daughter from the other. So it is clear (I think; I'm not a geneticist any more than I am a cultural anthropologist) that Amparo and Begonia are more closely related than most people are to their cousins. But what do we call people in that relationship? Double cousins?

Now for the updates (posted April 14)...

The answer to what anthropologists call the relationship (information mailed to me overnight by several people, including people that I would have talked to at the water cooler if I had been at Language Log Plaza) is that Amparo and Begonia are bilateral parallel cousins. If I have it right (with a lot of help from my friends, Molly Aplet especially), that is the technical name for the relation that holds between two people if their fathers are brothers and their mothers are sisters. In an earlier version of this update I said that Amparo and Begonia are bilateral cross cousins. That is a closely related notion; it would hold between Amparo and Begonia if Amparo's father and Begonia's mother were brother and sister, and Amparo's mother was the sister of Begonia's father. The term "double first cousins" has also been used in less technical contexts for both of these relationships (bilateral parallel cousinhood and bilateral cross cousinhood), and Jonathan Lundell tells me that the term his family always used was indeed the one I guessed at the outset, "double cousins". (I just knew there would be some kind of everyday terminology for it.) On the genetics question (how close is the relationship?), this discussion by a geneticist describes it as hard, and gives an inconclusive but informative review of the issues. Australian linguist David Nash has pointed out to me that p.9 of Mathematical Population Genetics by Warren J. Ewens (2004; acknowledgments to Amazon.com's Search Inside feature) says the correlation for double first cousins is slightly higher than that between an uncle and nephew, but a fair bit less than between full siblings, citing Fisher (1918), but that may be about phenotypes. Chris Maloof thinks the answer regarding genotypes is "easy to get with even high school biology": he says, "The genetic relatedness of double cousins is just 1/4, the same as an uncle to a nephew . . . One cousin shares 1/4 of his genes with his aunt and with his uncle (who are unrelated), so he'll also share 1/4 of his genes with their offspring." That's what we have for you at the moment (Fri Apr 14 13:43:59 EDT 2006).

Acknowledgments to: Molly Aplet, John Cowan, Karen Davis, Mark Liberman, Jonathan Lundell, Chris Maloof, Marilyn Martin, David Nash, Ben Zimmer, and abnu at WordLab. Thank you all.

Posted by Geoffrey K. Pullum at April 13, 2006 09:16 PM