Well I used to be very short fused, violent, was diagnosed with depression and mental illness earlier on in my life, had addictions and my father was exactly the same- however it has to be said that if I had to jump one way or the other in the nature vs nurture stakes I would largely go with nurture, as since I removed myself from the problem location, problem people and problem lifestyle, actually took the time and trouble to relearn my responses to situations and stress ( not easy or quick) I have been largely problem free and not taking any medication for it now for a very long time. That being said I'm still probably more likely to be deeply affected by some things than most people, and likewise probably more likely to want to solve problems by chucking someone through a window, but in my own case despite my father being a total sociopath I think I've largely overcome any inherant tendencies by careful life management.