Final answer:
Freud's psychoanalytic theory proposes that the incest taboo is a societal norm enforced through religious beliefs, meant to suppress the Oedipal complex and maintain social order.
Step-by-step explanation:
One theory that explains the incest taboo is the psychoanalytic theory proposed by Sigmund Freud. Freud believed that the taboo stems from unconscious desires that are repressed to maintain social order. In his work, Totem and Taboo, he argues that religious beliefs and societal regulations emerge to suppress deep-seated antisocial instincts, such as the incestuous desires outlined in the Oedipal complex. In this complex, Freud suggests there is an unconscious desire among males for their mothers and among females for their fathers. The incest taboo is essential, according to Freud, because if these desires were acknowledged or acted upon, the resulting chaos would be detrimental to the fabric of society.