A behavior genetic analysis of the tendency for youth to associate according to GPA

• Research suggests peers resemble one another on a host of traits.
• Cognitive ability often shows moderate-to-strong correlation between peers.
• Our findings reveal a correlation among peers in respect to their GPA.
• ACE model results show genetic factors explain 72% of the variance in peer GPA.

Behavior genetic research has revealed that many “environmental” variables are partially influenced by genetic factors. Known as gene–environment correlation (rGE), this line of scholarship provides insight on how and why individuals select into certain environments. Juxtaposing this body of evidence with research on peer group homophily—the tendency for peers to resemble one another on certain traits such as academic ability—raised two research hypotheses: (1) youth will associate with peers who receive grades similar to themselves (i.e., homophily for GPA); and (2) a portion of the variance in peer group GPA (i.e., the peer network average GPA) will be explained by individuals’ genetic self-selection into the peer group (rGE). The results supported both hypotheses by showing a strong predictive relationship between the target individual's GPA and that of his/her peers and by revealing that 72% of the variance in peer group GPA was explained by genetic influences.