Genetic and environmental causes of covariation in interview assessments of disruptive behavior in child and adolescent twins

Multirater, face-to-face, interview data relating to conduct disorder (CD), oppositional-defiant disorder (ODD), and inattentive, impulsive, and hyper active components of attention-deficit hyperactivity disorder (ADHD) in a p opulation-based sample of 1376 pairs of 8- to 16-year-old MZ and DZ twins a re analyzed to examine (1) the genetic and environmental causes of correlat ion among ratings of ODD and CD symptoms and (2) the pattern of genetic and environmental correlation among the three components of ADHD. Parental rat ings of ADHD showed marked sibling contrast effects, specific within raters but partly common across components. After these effects were removed, the re was a modest genetic correlation between maternal and paternal ratings, but genetic effects were virtually uncorrelated across boys and girls. Gene tic correlations among inattention, impulsivity, and hyperactivity were all large but fell well short of unity. There was little evidence that counts of symptoms of CD and ODD were genetically independent but the genetic corr elations among ratings of twins, mothers, and fathers were all relatively m odest. ODD and CD showed much higher genetic correlations across sexes than did the measures of ADHD. There was no evidence of rater contrast effects or of shared family environment influences in the twin resemblance for ODD and CD.