All human societies have at least some form of incest taboo.

Question

Quizplus · Accepted Answer

While the specific rules and enforcement of incest taboos vary across cultures, all known societies have some kind of prohibition against sexual relations between closely related individuals. This can include siblings, parents and children, grandparents and grandchildren, and other close relatives. The reasons for these taboos may be to prevent inbreeding, protect family structures, or reinforce social norms and values.

All Human Societies Have at Least Some Form of Incest