Beat me to it. Here's a précis:

James Fallon is a neuroscientist who researches the brain physiology of criminality. It turns out his brain scans are indistinguishable from those of psychopathic killers, his ancestry includes violent killers, he has all the high-risk alleles for violence, and his family, friends, and in particular, his psychiatric collaborators with expertise in the behavior of psychopaths all characterize him as kind of a sociopath -- possessing a certain glib charm but lacking in the ability to genuinely connect.