Hey, You Look Familiar

November 27, 2009 7:36 PM

If a woman had a son with Mr. X, then a subsequent son by Mr. X's brother, what would the childrens' relationship to each other be?

The kids would be half-brothers but also cousins; is there a specific word to describe that relationship? (BTW, this is a hypothetical question spawned by a movie trailer; there are no baby daddy issues lurking in it.)

posted by sfkiddo to human relations (11 answers total)

For intestate succession purposes, they would be brothers due to the mother. The closest relationship is the correct term.
posted by 2legit2quit at 7:39 PM on November 27, 2009

Wouldn't they be half-brothers and also first cousins?
posted by Issithe at 7:41 PM on November 27, 2009

Technically yes, but practically no.
posted by 2legit2quit at 7:45 PM on November 27, 2009 [1 favorite]

This is my dad's family. Oldest three are from one brother, younger two are from the other. They are brothers and sisters. The second brother (dad) actually adopted the older three, so it is official. In our case there were marriages. First to the older brother, then to the younger one.

This is actually the least of the family drama.
posted by TooFewShoes at 7:57 PM on November 27, 2009 [6 favorites]

You're right that they would be half-brothers as well as cousins, but for genealogical purposes, they would simply be referred to as half-brothers because the closer primary relationship takes priority over the incidental one.
posted by amyms at 8:00 PM on November 27, 2009

I knew a family like this where the brothers involved were identical twins, and the kids were still considered simply half-siblings.
posted by escabeche at 8:08 PM on November 27, 2009 [3 favorites]

This happens in royal families a lot (no surprise there) and as 2legit and others have said, the closest relationship is the one that is "recorded by history", though the others are also true.

So they're (half)-brothers and also cousins... which is exactly where you started with your question.

(Also, escabeche's example gave me a headache, but I get it on fourth reading.)
posted by rokusan at 10:04 PM on November 27, 2009

If my very armchair layperson understanding of genetics is right, they would be more genetically similar than regular half brothers because their fathers, as full brothers, would share genes as well-- different from if their fathers were not related.
posted by ishotjr at 11:46 PM on November 27, 2009

I have two aunts that married brothers and both had daughters. Then went on to divorce and remarry and have other children with these different men. These cousins of mine, who are also cousins to each other look so much alike that I was always confused which one I was looking at in pictures(didn't see them much in person while growing up)
Are they closer genetically than they are to their half-siblings?
posted by Jazz Hands at 6:24 AM on November 28, 2009

Three-quarters brothers. Or half-brothers plus plus. If the fathers strongly took after opposing parents it would be closer to half. If the fathers both strongly took after the same one of the parents, it would be closer to full.

We need a cattle or horse breeder in this ask met to supply us with the subtle subtleties of what is possible.
posted by bukvich at 11:43 AM on November 28, 2009

You're overthinking a plate of human beans.

If you do genealogy at all, you'll eventually find one or two of these sorts of multiple relationships between the same people. The closest one is generally the one that is recorded. Since there are all sorts of different ways this can go, there aren't special words for it.

I'm trying to remember one involving a couple of US politicians from the 19th century, where the nephew married the younger sister of his uncle's wife, or some such. Happened all the time, really.
posted by dhartung at 1:52 PM on November 28, 2009