What percentage of serial killers had bad childhoods?

In a study presented by the Journal of Police and Criminal Psychology featuring 50 serial killers, troubled childhoods were higher than the societal average. Over one-third were shown to have a history of physical abuse, 26 percent were sexually abused, 50 percent were psychologically abused and 18 percent were neglected.

While a difficult childhood has occasionally been linked to serial killer pasts, psychopathy is a more telling trait. Psychopathy is personality disorder with traits that include a charming personality, manipulation, aggressive behavior, blunt emotions and lack of remorse. Not all individuals who suffer from pyschopathy are serial killers, but psychopathic behavior is more of a commonality in serial killers than child abuse. It's important to note that there is no single cause or factor that creates a serial killer.