The non-specific genetic risk score for externalizing disorders was a composite measure of the parents’ (at baseline) and co-twin’s (at interview) criterion counts of Conduct Disorder (CD) (age 14) and Antisocial Personality Disorder (ASPD) (age 22). Throughout this manuscript, we will describe the adolescent antisocial criteria as CD and the adult criteria as Antisocial Behavior (ASB). As mentioned above, scores from monozygotic (MZ) co-twins were weighted twice as strongly as scores from dizygotic (DZ) co-twins or parents. Because this method equates the genetic relationship of parents and offspring and siblings, an additive model is assumed. EXT-GRs were computed on 1,312 participants.
