The incestuous marriages among members of the royal households of Europe were intended to preserve the familial property and expand the clan's territory. They were normative, not aberrant. Marrying an outsider was considered abhorrent.

An incestuous society - where incest is the norm - is conceivable even today.

Two out of many possible scenarios:

1. "The Lot Scenario"

A plague or some other natural disaster decimate the population of planet Earth. People remain alive only in isolated clusters, co-habiting only with their closest kin. Surely incestuous procreation is preferable to virtuous extermination. Incest becomes normative.

Incest is as entrenched a taboo as cannibalism. Yet, it is better to eat the flesh of your dead football team mates than perish high up on the Andes (a harrowing tale of survival recounted in the book and eponymous film, "Alive").

2. The Egyptian Scenario

Resources become so scarce that family units scramble to keep them exclusively within the clan.

Exogamy - marrying outside the clan - amounts to a unilateral transfer of scarce resources to outsiders and strangers. Incest becomes an economic imperative.

An incestuous society would be either utopian or dystopian, depending on the reader's point of view - but that it is possible is doubtless.

next: The Cultural Narcissist: Lasch in an Age of Diminishing Expectations