Causes of Violence
Why do be become violent? Is it from their environment or from their heredity?
Unfortunately, There are no simple answers to this question. Both the causes you mention can play a role. I would recommend a visit to your local college library where you would be able to search the literature for further information. I would ask the librarian to assist you in searching Medline and Psychinfo as a start. Good luck!
For more information:
Go to the Domestic Violence health topic.