I work in the criminal justice system and most psychopaths tried in death penalty cases have profound neglect and abuse in their childhoods. Brain development research indicates that consistent abuse and neglect of infants probably causes their developing brains to miswire and fail to make the "empathy" connections that normal babies make. Google Bruce Perry and Bessel van der Kolk.
That being said. some on trial have no apparent reason that they seem to lack empathy. I can easily believe that the miswire could be caused by biology (born that way) or environment. All of us have biological glitches but most of us are lucky enough to have the ones that can be medically diagnosed and treated.
