Incest Taboos and Kinship: A Biological or a Cultural Story?

In most, if not all, societies, incest taboos-perhaps the most universal of cultural taboos-include prohibitions on marriage between parent and child or between siblings. This universality suggests a biological origin, yet the considerable variation across societies in the full range of prohibited marriage relations implies a cultural origin. Correspondingly, theories regarding the origin of incest taboos vary from those that focus on the biological consequences (were marriage-based procreation allowed to include inbred matings) to those that focus on social consequences such as confounding social roles, especially within the family, or restricting networks of interfamily alliances, were marriages to take place between close relatives. For those focusing on the biological consequences, the sexual aversion hypothesis of the anthropologist Edvard Westermarck has played a central role through seemingly providing an empirically grounded, causal link from the phenomenal level of behavior to the ideational level of culture. Yet the matter is not so simple and requires rethinking of what we mean by kinship and how our ideas about kinship relate to the widespread occurrence of incest taboos and the extensive variability in their content.