de Harold Schechter
Deploying state-of-the-art MRIs and other high-tech devices to scan the brains of imprisoned psychopatic killers, researchers such as Kent Kiehl of the University of New Mexico and Jim Fallon of the University of California have become convinced that damage to those areas of the brain responsible for compassion, inhibition, and moral choice can significantly reduce a person's reluctance to harm others.
Even proponents of this theory, however, concede that other factors have to be present to turn someone into a serial killer.
Extreme parental maltreatment is prominent among them. (...) Some genetic component might also be at work.
In short, it appears to require a witch's brew of three toxic ingredients to produce a serial murderer: damage to particular brain areas, extreme childhood abuse, and an inheritance of specifi genes thought to be associated with aggression and violence.