Links between friends’ physical aggression and adolescents’ physical aggression

Abstract

Exposure to deviant friends has been found to be a powerful source of influence on children's and adolescents' aggressive behavior. However, the contribution of deviant friends may have been overestimated because of a possible non-accounted gene-environment correlation (rGE). In this study, we used a cross-lagged design to test whether friends' physical aggression at age 10 predicts an increase in participants' physical aggression from age 10 to age 13 years. Participants were 201 pairs of monozygotic twins who are part of the Quebec Longitudinal Twin Study. We performed two sets of analyses. In the first set of analyses, using twins as singletons, we found that teacher-rated friends' physical aggression predicted an increase in each twin's self-reported physical aggression from age 10 to age 13, above and beyond auto-regressive and concurrent links. Second, we used within-pair differences in regard to friends' physical aggression to predict an increase in within-pair differences in physical aggression, thus accounting for family-wide influences, including a likely rGE at age 10. No significant association was found, however. These results suggest that part of the influence attributed to friends in past studies may have been due to common underlying genetic effects on both physical aggression and association with physically aggressive friends.

Do MZ twins have discordant experiences of friendship? A qualitative hypothesis-generating MZ twin differences study

“…The researchers found the positive dimension to be moderately heritable (h 2 = .31) but the negative dimension to be primarily explained by NSE effects. Other studies have noted evidence of genotype correlation as an explanation of, for instance, the association between peer victimization and physical ill health [ 26 ] and the association between peer aggression and aggressive behaviour [ 27 ]. In summary, the picture is somewhat unclear but it is true to say that all studies find NSE factors to explain variation in peer relationships.…”

Paradigm shift or normal science? The future of (biosocial) criminology

“…For example, Sutherland’s differential association theory was constructed, in part, to disavow the notion that biological factors were related to criminal behavior (Bernard, 2008). Today, rather than directly denying the relevance of biology or the environment, certain work may ignore biology (see Barnes et al, 2014), argue that current iterations of biological criminology are misguided or unproductive (Carrier and Walby, 2011; 2015), or seek to show that particular environmental factors do not influence behavior (Beaver et al, 2015; Vitaro et al, 2016). At this point, it is clear that biology and the environment conspire to produce criminal outcomes.…”

Evaluation of the Problem Behavior Frequency Scale–Teacher Report Form for assessing behavior in a sample of urban adolescents.

“…Some teacher-report measures include aggression or bullying scales but do not differentiate among forms of aggression (e.g., Gresham & Elliott, 2008;Reynolds & Kamphaus, 2004). Others assess only a single form of aggression (e.g., Vitaro et al, 2016). Assessing multiple forms of aggression can provide useful information.…”