The prohibition of marriage and sexual relations between particular categories of kinsmen.
Comment:Sexual relations between parents and children are extremely rarely reported for living non-human primates, and from this it is reasoned that incest taboos have a basis either in a biological lack of sexual attraction between parents and children or in a disinclination toward sexual contact rooted in a child's experience of total dominance by parents (especially mothers) during infancy.
Among humans, all societies prohibit marriage with close kinsmen, always including parents with children and siblings with each other. (A trivial exception involves preferential sibling marriage to preserve the "purity" of some royal lines.) In most cases, this "incest taboo" is also extended to some other kinship classes, but these vary by society.
Not surprisingly, sexual relations do occur in violation of the incest taboo, and societies vary in the severity with which they punish them. Therefore what is universal is the impossibility of recognized marriage and positively sanctioned sexual contact among the prohibited categories, not the actual occurance of sexual relationships.
What has attracted attention has been the issue of universality. Some scholars have argued that the critical factor is the often observed lack of sexual attraction between adolescents (or adults) if they have experienced intimate non-sexual contact through childhood (a typical brother-sister relationship), but that does not explain the need for a cultural "rule." If people don't want to do it, why must it be explicitly prohibited?
Others have sought an explanation in the evolutionary advantages of exogamy in sustaining relationships between groups. That does not explain why a prohibition would need to be absolute either, since presumably very few marriages would be incestuous merely because they were permitted to be.
Countless other lines of logic have also been speculatively proposed.
At this time, although the term "incest taboo" remains useful, and although the phenomenon continues to be universal when defined as marriage prohibition, a fully satisfying explanation of the universality of the taboo remains elusive.
Definition Revised: 2011-10-08
Script Last Modified: 2025-02-04
Search term: "incest" (Debugging)