While studying brain scans of several family members, he discovered that one perfectly matched a pattern he d found in the brains of serial killers. This meant one of two things: Either his family s scans had been mixed up with those of felons or someone in his family was a psychopath.Even more disturbing: The scan in question was his own.This is Fallon s account of coming to grips with this discovery and its implications. How could he, a happy family man who had never been prone to violence, be a psychopath? How much did his biology influence his behavior?Fallon shares his journey to answer these questions and the discoveries that ultimately led to his conclusion: Despite everything science can teach, humans are even more complex than we can imagine."