Most psychologists who have studied the question of how aggression operates are convinced that everyone learns violent behavior by seeing it enacted, ready or not. The more prestigious the person modeling aggressive behavior, the more likely it is to be imitated by observers. Imitation, after all, is an indispensable way that an intelligent species like ours learns. Children do it. Teen-agers do it.
Grownups do it.
Mindlessly we automatically imitate and follow the leader. Athletes will watch videos depicting images of excellent moves to increase their own proficiency. Anything we notice and process gets put into the information programs in our minds and memories. One is the behavioral sequence, how, for instance, to go about setting fire to a vagrant sleeping on a park bench. Taboos lose their inhibitory force.