If a G × E interaction is present, the initial ACE parameters derived from the bivariate model are then adjusted based on the direction (+ or -) and size of the moderation weight (βxij) and the level of the moderator (M; e.g., number of antisocial peers). Moderation can occur for either the ACE effects that overlap between EXT and the environmental risk factor (e.g., a21 + βa21*M) or those ACE effects that are unique to EXT (e.g., a22 + βa22*M). For example, a positive sign for βa22 would mean that the unique genetic variance in EXT would increase in the context of more antisocial peers.
