An incest taboo is any cultural rule or norm that prohibits sexual relations between certain members of the same family, mainly between individuals related by blood. All human cultures have norms that exclude certain close relatives from those considered suitable or permissible sexual or marriage partners, making such relationships taboo. However, different norms exist among cultures as to which blood relations are permissible as sexual partners and which are not. Sexual relations between related persons which are subject to the taboo are called incestuous relationships. Some cultures proscribe sexual relations between clan-members, even when no traceable biological relationship exists, while members of other clans are permissible irrespective of the existence of a biological relationship. In many cultures, certain types of cousin relations are preferred as sexual and marital partners, whereas in others these are taboo. Some cultures permit sexual and marital relations between aunts/uncles and nephews/nieces. In some instances, brother–sister marriages have been practised by the elites with some regularity. Parent–child
Un tabú de incesto es cualquier regla o norma cultural que prohíbe las relaciones sexuales entre ciertos miembros de la misma familia, principalmente entre individuos relacionados por la sangre. Todas las culturas humanas tienen normas que excluyen a ciertos parientes cercanos de aquellos que se consideran apropiados o permisibles para relaciones sexuales o matrimoniales, haciendo que tales relaciones sean tabú. Sin embargo, existen diferentes normas entre culturas en cuanto a cuáles las relaciones de sangre son permisibles como parejas sexuales y cuáles no. En muchas culturas, ciertos tipos de relaciones de primos son preferidos como parejas sexuales y matrimoniales, donde en otras culturas son tabúes. Algunas culturas permiten relaciones sexuales y matrimoniales entre parejas y sobrinos.