Background: A recent meta-analysis revealed moderate shared environmental influences (C) on most forms of child and adolescent psychopathology (Burt, 2009), including antisocial behavior. Critically, however, the research analyzed in this meta-analysis relied largely on specific informant-reports (and particularly parent and child reports), each…

Behavioral genetic research has concluded that the more important environmental influences result in differences between siblings (referred to as "nonshared"; "e[superscript 2]"), whereas environmental influences that create similarities between siblings (referred to as "shared"; "c[superscript 2]") are indistinguishable from zero. However, there…