A large part of childhood is spent learning how to keep aggressive feelings from spilling over into physical violence. Aggressiveness is not bad in itself, in fact it's a God-given attribute. Without it we would never achieve anything. However, in order for people to live together in communities, violent aggression must be controlled somehow. This is done through laws and sanctions, as well as by training children to control their violent impulses in situations where they are considered inappropriate.
Different societies tolerate differing degrees of violence.
With two world wars and Vietnam still within living memory, our own society has become sensitive to, and intolerant of, many forms of overt violence. Yet the human lust for violence expresses itself in other ways. Violence has become identified with entertainment in a way not seen since Roman times, through TV, film, videos and games. Concern about the dangers of children being exposed to such violent material is common, but the question of what effect it has on adults is asked less often. The few studies which have been done with adults suggest that after viewing even fictitious violence, people become more fearful and anxious about the real world, less sympathetic to victims and less likely to go to their aid.