Persons who engage in violence tend to have been victims of violence. Every time a child is punished by the use of violence he is being taught that the use of violence is a proper mode of behavior.
Violence becomes what superego figures do.
It is impossible to use corporal punishment on a child without simultaneously teaching that the deliberate infliction of pain as a form of persuasion and as a means of gaining ascendancy over others is legitimate. The child who is witness to adult violence also quite rightly asks himself why he may not use violence in order to make other people behave in accordance with his wishes. The answer he comes to is simply that he does not have sufficient physical and social might to inflict pain on others without their retaliating. All that he lacks is power. And as soon as he gets it, he takes it as right that he should use it.