January 20, 2011
Brain Genes Influence Friend Choices

Maybe some day you won't friend someone on Facebook without first checking for genetic compatibility. A paper published in PNAS finds that dopamine receptor gene DRD2 seems to cause people to befriend those who also have the same genetic variant whereas with another gene called CYP2A6 the opposite seems to be the case.

With one gene, called DRD2, which has been associated with alcoholism, they found clusters of friends with the very same marker.

Another gene called CYP2A6, which has a suspected role in the metabolism of foreign bodies including nicotine, appeared more divisive. People with this gene seemed to steer clear of those who also carry the gene.

DRD2's previous known association with alcoholism might give a clue to this result. Maybe social drinkers are more likely to form friendships with other social drinkers.

Why would people with open personalities avoid those who also have open personalities?

People who had a genetic variant of a gene associated with an open personality, CYAP26, tended to have friends who did not share this genetic variant.

Are you feeling metagenomic about your friends?

A replication study in an independent sample from the Framingham Heart Study verifies that DRD2 exhibits significant homophily and that CYP2A6 exhibits significant heterophily. These unique results show that homophily and heterophily obtain on a genetic (indeed, an allelic) level, which has implications for the study of population genetics and social behavior. In particular, the results suggest that association tests should include friendsí genes and that theories of evolution should take into account the fact that humans might, in some sense, be metagenomic with respect to the humans around them.

I see a way to use this line of research: You know how it is that parents do not want their kids associating with the wrong types? Well, in the future prospective parents will be able to choose genetic variants that will assure that many years later Johnnie or Jill won't want to associate with troublemakers and apprentice criminals in high school. Just give your babies genes that make them feel aversion to bad influences.

Share |      Randall Parker, 2011 January 20 12:05 AM  Brain Genetics

Billy the Kid said at January 20, 2011 4:55 PM:

So... people with similar interests tend to group together? ...Got it.

Ruy Diaz said at January 21, 2011 10:55 AM:

Seems like Futurepundit needs to get readers who share his level of curiosity about the world. Not much luck so far....

Randall Parker said at January 21, 2011 11:47 PM:


Heavy sigh...

Di said at January 22, 2011 12:34 AM:

I don't know my genome, but I'm quite outgoing, and several of my best and oldest friends are very un-outgoing, even painfully shy. Hmm...

BioBob said at January 22, 2011 1:02 AM:

Randall, apparently a lot of skepticism bout this one out there in genetics land...a lot.

LAG said at January 22, 2011 10:20 AM:

"You know how it is that parents do not want their kids associating with the wrong types?"

The problem with this is whose genetics will the parents choose to match? Theirs or the yet to be constructed off-spring? Do you want to hook up with a bunch of people who are best suited as matches for your mom and pop?

Kaci said at January 22, 2011 2:46 PM:

This is the "nature" part of your friendships and camaraderie, then. The "nurture" part is not affected. So yes, while on some level, you would tend to hang around groups of people with similar intelligence levels, for instance, that does not say that one cannot make friends non-intelligent people.

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