Genetic effects explain the stability of psychopathic personality from mid- to late adolescence

This study examined the importance of genetic and environmental influence for the stability of psychopathic personality between mid- and late adolescence. The target sample consisted of all 1,480 male and female twin pairs born in Sweden between 1985 and 1986. Psychopathic personality was measured with the Youth Psychopathic Traits Inventory (YPI; H. Andershed, M. Kerr, M. Stattin, & S. Levander, 2002) when the participants were 16 and 19 years old. Results showed that the 3 psychopathic personality dimensions were stable at different levels of analysis and linked to a stable higher order general factor (i.e., psychopathic personality factor). Genetic factors contributed substantially to the stability of this general higher order factor, whereas environmental factors were of little importance. However, the authors also found specific genetic stability in the Callous/unemotional and Impulsive/irresponsible dimension. Thus, the model provides evidence for etiologic generality and etiologic specificity for the stability of psychopathic personality between mid- and late adolescence.