Background: Psychopaths are not only antisocial, but also have a callous and unemotional personality profile. This article selectively reviews evidence that psychopathic personality traits are an important factor in understanding and predicting the development of persistent antisocial conduct. Cognitive neuroscience research and more tentative genetic work on psychopathy will be discussed, especially as they relate to possible developmental trajectories to psychopathy. Results: A personality-based approach has been successful in clarifying the conceptual boundaries of psychopathy and delineating a group of antisocial individuals with a distinct profile of offending and clear neurocognitive markers indicating problems in processing distress in others and punishment directed to oneself. These markers are also present in children with psychopathic tendencies, suggesting that psychopathy may be a developmental disorder. The neurocognitive profile relates to the callous and unemotional personality traits at the core of psychopathy and may index particular vulnerability to persistent antisocial conduct. Preliminary twin studies suggest that personality traits at the core of psychopathy are much more highly heritable than other personality traits. There are as yet no molecular genetic studies of psychopathy. Conclusions: It is argued that an interdisciplinary approach that integrates cognitive neuroscience and genetics will enhance understanding of the development of psychopathy.