heritability estimates on the order of 40–50% in both boys and girls.8 A review of > 100 quantitative genetic studies of antisocial behavior (measured using various methods) converged on a heritability estimate of 50%,9 and a recent multi-informant study of childhood antisocial behavior showed evidence of even stronger genetic influence.10 Furthermore, twin studies indicate that genetic influences on CD show considerable overlap with alcohol and other substance dependence.11–14
