Further, research from the past decade has suggested that genetic liability could be a moderator of the relationship between exposure to peer behavior and adolescents’ own behavior. Adolescents have genetically influenced individual differences that render them more or less susceptible to peer influence (i.e., a gene – environment interaction; Rutter & Silberg, 2002). A study by Harden, Hill, Turkheimer, and Emery (2008) found that the impact of best friends’ substance use on target adolescents’ use was most pronounced for adolescents with the highest genetic vulnerability for using tobacco and alcohol. This interaction also has been observed for other outcomes and at various ages. In two samples of young twins, youth were most likely to be physically aggressive if they were both genetically liable for this behavior and were exposed to highly aggressive peers (Brendgen et al., 2008; van Lier et al., 2007).
