SNPs Foster Friendships?

Researchers at Harvard and UC San Diego published a paper online in advance in PNAS this week showing that "maps of friendship networks show clustering of genotypes." Using six available genotypes from the National Longitudinal Study of Adolescent Health, the team mapped genetic similarities among more than 3,000 friend pairs and found that, when controlled for population stratification, "one genotype is positively correlated (homophily) and one genotype is negatively correlated (heterophily)." Nature News reports on this "opposites attract" phenomenon, adding that the researchers found that friends "tended to have the same SNP at one position in a gene encoding the dopamine D2 receptor, DRD2," and in addition, "showed more variation at one position in a cytochrome gene, CYP2A6, than non-friends." In its paper, the researchers say that their study not only open doors for future genetics research on social behavior, but also "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." Lead author James Fowler told The Scientist that "there's something about Mary that draws you to her … researchers haven't figured out what that something is."