human violence
there are numerous reasons for the existence of criminal violence. Many of these reasons revolve around disadvantaged living conditions, including poverty, unemployment, divorce, and so one. However, much of the research into violence has focused on certain kinds of personality, especially anti-social personality disorder and psychopathy. Individuals with antisocial personality discoder are aggressive, and their behaviour is often irresponsible and unlawful, showing a disregard of social conventions. There are far more men than women  with antisocial personality disorder, possibly four or five ties as many. Individuals with psychopathy have very poor behaviour control, they lack empathy, and they show little or no remorse after hurting other people. There are convincing links between these personality disorders and criminality. About 40% - 50% of prisoners in American prisons have antisocial personality disorder, and a further 25%-30% have psyhopathy.