Survival on this planet, inherently involves violence and so do human instincts for establishing social hierarchies (reference: Social dominance theory). Virtually any human being faces violence (at least) at some stage of their life.
Therefore we can state that aggression always finds its place in human psyche. While all of us possess some aggression we do express it in different manners. Some of us repress it, others let it explode uncontrollably, still others try to direct it at the source of violence against them, etc.
a) Is there any research what happens when a person is put in (the unnatural) circumstances of so low levels of violence in their life, that we could assume that violence stimuli are actually absent?
b) If there's no research done, what would you expect to happen (based on professional experience or your scientific reasoning) - e.g. having an individual totally incapable of aggressive behaviour that they cannot defend themselves under life-threatening circumstances or just the contrary - an individual becoming violent out of no reason, or something else?