Abstract
Some behavioural overlap exists between psychopathic tendencies and autistic traits, and both phenotypes are thought to be associated with problems in empathy. However, the broad behavioural profiles and the cognitive-affective deficits associated with the two conditions are at least partly separable. The main aim of this study was to assess the extent to which the aetiology of psychopathic tendencies is independent of autistic traits. A secondary aim was to study the aetiology of emotion attribution ability and its association with psychopathic tendencies and autistic traits. Based on data from a sample of 642 twin pairs, the genetic and nonshared environmental influences related to psychopathic tendencies were largely unique to each phenotype. Common environmental influences between psychopathic tendencies and autistic traits overlapped. Poorer emotion attribution ability was associated with increased psychopathic tendencies and autistic traits, and these associations were mainly explained by common genetic factors.