Non-shared Environmental Mediation of the Association between Deviant Peer Affiliation and Adolescent Externalizing Behaviors over Time: Results from a Cross-lagged Monozygotic Twin Differences Design

摘要

It has been argued that peers are the most important agent of adolescent socialization, and more specifically, that this socialization process occurs at the child-specific (or non-shared environmental) level (; ). The present study sought to empirically evaluate this non-shared environmental peer influence hypothesis, examining the association between externalizing behaviors and deviant peer affiliation in a sample of 454 pairs of monozygotic (genetically identical) twins, assessed at ages 14 and 17, within a cross-lagged twin differences design. Results argued against a causal non-shared environmental influence of peer affiliation on the development of externalizing behaviors, and in favor of non-shared environmental “selection”. In particular, the twin with more externalizing behaviors at age 14 reported increased deviant peer affiliation relative to his or her co-twin three years later, regardless of one’s genetic predispositions towards externalizing behavior. Such findings suggest that adolescents with higher levels of externalizing behaviors select or shape (either intentionally or inadvertently) subsequent environmental experiences to involve increased affiliation with deviant peers. Implications are discussed.