Actually child abuse will dramatically make a person more susceptible to do certain things, like rape, killing, stealing etc etc. I don't think you can say 100% that their past has no sway on aggression and the like. All of our actions are influenced by past events.
Of course our actions are influenced by the past. But we CHOOSE to handle the future in preferably non-aggressive ways despite our past. All of us can fly off the handle or get mad or throw things. All of us have said, "I could just kill so-and-so". But how many take it that far? Very few, because we can control that agrression. My point is that for the ones who cannot control it, there may very well be a logical explanation in the hormone elevation. Lower that and the person is able to exert their choices again