The woman, who constantly does nothing in the domestic matter, is considered inappropriate, the husband, who does nothing in the same way, - just bad, although transient (to husbands the criteria of utility are underestimated compared to wives, but husbands still don't like uselessness), the child's criteria of utility gradually increase and, although initially soft, but gradually exceed even those that the husband has. And only a cat can not bring any practical benefit at all, and at the same time give the owner the maximum of warmth and happiness.