Background: Psychopathy is characterised by profound deficits in the human tendency to feel and care about what other people feel, often known as "affective empathy". On the other hand, the psychopath often has intact "cognitive" empathy skills, that is, he is able to describe what and why other people feel, even if he does not share or care about those feelings. Despite a rapidly advancing neuroscience of empathy, little is known about the developmental underpinnings of this psychopathic disconnect between affective and cognitive empathy. Methods: The parents of N = 2760, 3-13-year-olds reported on the levels of empathy, callous-unemotional traits (CU), and antisocial behaviour (AB). Consistent with current theory and measurement practice, an index of "psychopathic traits" was derived from the CU and AB measures. Results: There are important gender and developmental differences in empathy deficits related to psychopathic traits. As expected, psychopathy is associated with severe deficits in affective empathy across all ages for males; however, no such deficits were found for females. Contrary to adult findings, psychopathic traits are associated with deficits in cognitive empathy in childhood for both sexes; however, males with high psychopathic traits appear to overcome these deficits in cognitive empathy as they move through the pubertal years. Conclusions: In contrast to cognitive empathy, low affective empathy does not appear to be associated with psychopathic traits in females. The characteristic disconnect between cognitive and affective empathy seen in adult male psychopathy crystallises in the pubertal years when they appear to learn to "talk the talk" about other people's emotions, despite suffering severe deficits in their emotional connection (affective empathy) to others.