Aetiology of the relationship between callous-unemotional traits and conduct problems in childhood.

BACKGROUND A callous and unemotional disposition is an indicator of early-onset antisocial behaviour. AIMS To investigate the extent to which genetic influences contribute to the overlap between callous-unemotional traits and conduct problems in a large population sample of 7-year-old twins. METHOD Teachers provided ratings of callous-unemotional traits and conduct problems for 3434 twin pairs from the Twins Early Development Study. Model-fitting analyses were performed across the continuum of scores and at the extremes. RESULTS The phenotypic relationship was primarily genetically mediated, both across the continuum and at the extremes and was substantial. CONCLUSIONS At 7 years of age, genetic influences on callous-unemotional traits overlap substantially with genetic influences on conduct problems. This combination should guide selection criteria in future molecular genetic studies.