A taboo is a cultural proscription against a particular type of behavior. Some taboos, like the prohibition of incest or fratricide, are nearly universal among human societies, though they exist in somewhat different forms depending on cultural context. Others, like specific dietary restrictions or rules regarding the interactions between the sexes, are much more restricted. As the philosopher Abraham Edel observes, there are exceptions to every rule, and taboo behaviors are sometimes condoned;[1] The biographies of monarchs from around the world provide ample examples of culturally acceptable incest and fratricide, for example.