Humans speak out both sides of their mouths regarding violence, as they both adore violence and promote it as a solution to problems while at the same time asserting it is at the core of many problems their societies deals with. Sports such as football and boxing involve the deliberate injury of opponents, movies present conflict resolution via death by guns and knives and setting the opponent aflame, and yet when this same behavior is expressed by gangs of boys in the ghettos it is taken to be a sign of a sick society. Institutional violence such as police brutality is condoned while white collar crime by members of the elite classes is forgiven, but both actions bring severe reprimands if done by those not on top of the pile. The message is that violence is OK if you can get away with it. This can be seen most clearly in a comparison of how the expression of sexual desires is treated versus how the expression of violent tendencies is treated in toddlers.
Children in the playpen with each other can club each other over the head, throw objects at each other, or simulate murderous instincts in graphic play with dolls with scarcely a reprimand from their parents. The child may be temporarily separated from others it is hurting, and the victim comforted. That the behavior is unacceptable is hardly communicated, but what is communicated is that the behavior has limits. Violence is OK, but making Mary scream when mother is trying to chat on the phone is not OK - thats the message. The child then begins to learn how to express their violent tendencies where they wont get caught. If mother is not around or is busy in the kitchen rather than on the phone where she desires quiet, then pinching Mary or pummeling her over the head is OK.
Children in the playpen with each other, or even alone, cannot, however, get into sex play. Where the purported dangers of sex play - venereal disease and pregnancy, cannot possibly be present in the playpen, nevertheless the child is instantly told by the tone of the mothers voice and the intensity and quickness of her actions that such play is a serious infraction. Adults are intensely uncomfortable when a childs curious probing finger goes into the diaper. If such curious play has come to the mothers attention, the child is likely not to be left alone during play, and most certainly wont be left alone with other children if sex play has begun. The anxiety and resulting anger and fear that the mother expresses speak mountains to the toddler, who often develops such a parallel anxiety about sex that they are crippled for life in this arena.