16th
Genes and social networks: new research links genes to friendship networks
“James Fowler, a professor at UC-San Diego, is engaged in highly innovative and important research at the crossroads of political science and biology. His recent paper in the Proceedings of the National Academy of Sciences, “Correlated Genotypes in Friendship Networks”, represents an important new study in an emerging research field that is exploring the genetic and biological foundations for our political and social behavior. (…)
Genotypic clustering in social networks”, by statistically examining the association between markers for six different genes and the reported friendship networks from respondents in data from the National Longitudinal Study of Adolescent Health and the Framingham Heart Study Social Network. They show that one of these genes (DRD2) is positively associated with in friendship networks, meaning that those who have this gene are more likely to be friends with others who have this gene, controlling for demographic similarities and population stratification; another gene, CYP2A6 has a negative association in friendship networks. (…)
What is the most important implication of demonstrating that specific genes are associated with who we affiliate with in our friendship networks?
James Fowler: What happens to us may depend not only on our own genes but also on the genes of our friends. This has been shown already in hens, whose feathers change depending on the genetic constitution of the hens that are caged near them. But something similar may happen in humans. We each live in a sea of the genes of others. In fact, we are metagenomic. (…)
An important caveat is that there may be processes besides friendship choice that create correlated genotypes. Our genes may cause us to be drawn to certain environments where we are more likely to meet similar people. For example, people with the same DRD2 genotype might both find themselves in a bar where they then become friends. But this cannot explain *negative* correlation. The “opposites attrac” result with CYP2A6 is more likely to be due to friendship choice. (…)
But it is true there can be feedback effects — our genes not only influence us, but they may influence the genes of our friends, which in turn has an additional effect on us. For example, the DRD2 gene variant we study has been associated with alcoholism, and if you have this gene variant, your friends are likely to have it, too. So you are not only more susceptible to alcoholism yourself, but you are likely to be surrounded by friends who are susceptible, too. Thus, ignoring genes means we might miss important heterogeneity in the network that would obscure strong social effects. (…)
We have discovered some regularities in our studies of human social networks that suggest their structure may be universal, such as the tendency for many of our friends also to be friends with one another, and the tendency for influence to spread to about three degrees of separation. We conjecture that we have coevolved with these networks as our brains have gotten bigger, and genetic variation might give us a clue about which systems have undergone the most recent evolutionary changes.”
— A conversation with James Fowler by R. Michael Alvarez, Genes and social networks: new research links genes to friendship networks, Psychology Today, February 14, 2011. See also: Daniel MacArthur, On sharing genes with friends, Wired, Jan 19, 2011
