Adult friend search
Genetic similarity among friendship networks is important for at least two reasons.
Analyses focus on a group of genetically homogeneous respondents identified as being of ancestral European origin (. In step 1, we test whether friends are more genetically similar to one another than to randomly selected peers.
Recent research has evaluated the possibility that unobserved genotypes may play an important role in the creation of homophilous relationships.
We extend this work by using data from 5,500 adolescents from the National Longitudinal Study of Adolescent to Adult Health (Add Health) to examine genetic similarities among pairs of friends.
In a national sample of more than 5,000 American adolescents, we found evidence of social forces that act to make friends and schoolmates more genetically similar to one another compared with random pairs of unrelated individuals.
This subtle genetic similarity was observed across the entire genome and at sets of genomic locations linked with specific traits—educational attainment and body mass index—a phenomenon we term “social–genetic correlation.” We also find evidence of a “social–genetic effect” such that the genetics of a person’s friends and schoolmates influenced their own education, even after accounting for the person’s own genetics.