Children are all more or less little monkeys in that they imitate everything they see. If their mother treats them exactly as she does her visitors they in turn play "visitor" to perfection. Nothing hurts the feelings of children more than not being allowed to behave like grown persons when they think they are able.
Emily Post (2007). “Etiquette: In Society, in Business, in Politics and at Home”, p.577, Cosimo, Inc.