Friends
Kenneth Kendler, et al., found that genes strongly influence who we choose as friends. The researchers studied the peer groups of approximately 1,800 male twins between the ages of 8 and 25 years old, having each subject describe the level of “social deviance” among their friends, such as how many of their friends got drunk, used or sold drugs, or damaged property. The research showed that an individual’s selection of friends — whether they chose to socialize with fewer or more socially deviant peers — was shaped by genetic factors. Researchers also found that the influence of genes increased over time.
“You’ve Got to Have … Genes,” by Sarah Kliff