19.4 Critically assess different explanations for the universality of the incest taboo.
Romantic literature and Hollywood notwithstanding, marriage is seldom based solely on mutual love, independently discovered and expressed by the two life-partners-to-be. Nor is it based on sex or wealth alone. Even when love, sex, and economics are contributing factors, regulations specify whom one may or may not marry. Perhaps the most rigid regulation, found in all cultures, is the incest taboo, which prohibits sexual intercourse or marriage between some categories of kin.
The most universal aspect of the incest taboo is the prohibition of sexual intercourse or marriage between mother and son, father and daughter, and brother and sister. No society in recent times has permitted either sexual intercourse or marriage between those pairs. A few societies in the past, however, did permit incest, mostly within the royal and aristocratic families, though generally it was forbidden to the rest of the population. For example, the Incan and Hawaiian royal families allowed marriage within the family. Probably the best-known example of allowed incest involved Cleopatra of Egypt.
It seems clear that the Egyptian aristocracy and royalty indulged in father-daughter and brother-sister marriages. Cleopatra was married to two of her younger brothers at different times.47 The reasons seem to have been partly religious—a member of the family of the pharaoh, who was considered a god, could not marry any “ordinary” human—and partly economic, for marriage within the family kept the royal property undivided. Between 30 B.C. and A.D. 324, incest was allowed in ancient Egypt not only among the royal family but among commoners; an estimated 8 percent of commoner marriages were brother-sister marriages.48
In spite of such exceptions, no culture we know of today permits or accepts incest within the nuclear family. Why is the familial incest taboo universal? Several explanations have been suggested.