Lynn, in response to your post I would like to comment that it's probably both factors, heredity and environment.
I was the sister to a man who definately had showed the signs of antisocial personality disorder. Believe me it was very, very hard being his sister. His explosive rages and constant mistreament of me make me wonder at how I survived being his sister. Anyway, I digress. What I want to tell you and everyone else is that my younger brother was badly abused as a child by our father and as a infant he was always "cholicky". So that makes me wonder if both heredity and environment are responsible in my brother's case.