A body of research has examined the potential causes of psychopathy and psychopathic personality traits. What is surprisingly missing from these studies is an effort to estimate person–environment interactions that might explain variation in psychopathic personality traits. The current study addressed this lacuna, examining whether early-life temperament conditioned the effect of parental sensitivity on adolescent affective psychopathic personality traits. Drawing on data from the National Institute of Chlid Health and Human Development (NICHD) Study of Early Child Care and Youth Development, the results revealed some evidence of temperament–parenting interactions, which were more in line with a differential-susceptibility than a diathesis-stress model of environmental action. Findings indicated that male infants with an easy temperament were the most affected by maternal and paternal sensitivity when it came to predicting a measure of affective psychopathic traits and the subcomponent of callousness. In addition, early-life temperament also interacted with paternal sensitivity in a for-better-and-for-worse fashion for the subcomponent of unemotionality.