Consistently portrayed in the media and popular culture as unusual, inhumane and emotionless creatures, psychopaths may seem far removed from our everyday lives. The reality, however, brings them much closer to home: estimates suggest that a disturbing percentage of the population has psychopathic tendencies. This timely new book presents the scientific facts of psychopathy and antisocial behavior, addressing critical issues such as the definition of psychopathy, the number of psychopaths in society, whether psychopaths can be treated, and whether psychopathy is due to nature or nurture. More controversially, the authors present their ground-breaking research into whether an underlying abnormality in brain development leaves psychopaths with an inability to feel emotion or fear. The resulting theory could lead to early diagnosis and revolutionize the way society, the media, and the state both views and contends with the psychopaths in our midst.