The amygdala is the area of the brain where people process emotions. In psychopaths, this area is up to 18% smaller. When most people are given a moral dilemma to consider, such as the trolley problem, the amygdala fires up and lights up on brain scans. In psychopaths, this doesn’t happen to the same degree.
“We know that there are strong genetic contributions to the brain areas, but we also know that the social environment can impact the brain,” Raine said. “People who are abused early in life or who are neglected, for example, they have a reduction in the volume of the amygdala. That’s at least true in children. So it can be genes and it can be the environment. Most likely, it’s a combination of both.”