Our findings are instead more consistent with social or self selection processes which drive and underpin deviant peer affiliation (76). Snyder (6) has argued that individuals when operating in open environments offering elective relationships select and affiliate with others who are behaviourally similar. A number of mechanisms including temperament and maladaptive externalizing behaviours have been proposed to make individuals more likely to affiliate with deviant peers (5, 77, 78) and biometrical modeling has also shown that variation in the sorts of friends we choose and affiliate with can be partly explained by genes (79, 80) which is consistent with our data.
