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.