ABSTRACT
This chapter explores the nature of incestuous phantasies and activity in twins; the ways in which the twin relationship may affect marital relationships; and the transgenerational effect of twinning that becomes evident in parent-child relationships. Twinning, as a projected internal relationship, would be manifest in all the intimate relationships of a twin, and to this effect may influence the marital/partner relationships and parents' relationships with their children. The closeness of the twin relationship and its incestuous core may lead some twins to feel that any sexual activity external to the twinship is a betrayal of the other twin and is only second best to the twin incest. Heterosexual and homosexual investigation of siblings based on sexual curiosity is a common childhood experience and it is difficult to distinguish it from brother-sister or same-sex incestuous relationships. Twins may create jealousy and anxiety in their siblings, particularly as the twins tend to generate a greater than usual fuss around them.
