““If we grant that our evolutionary history did not prepare us to detect lies from demeanor, why do we not learn how to do so in the course of growing up? One possibility, and my second explanation, is that our parents teach us not to identify their lies. Their privacy may often require that they mislead their children about just what they are doing, when they are doing it, and why they are doing it. While sexual activity is one obvious focus of such lies, there might well be other activities that parents want to conceal from their children.””
