Twinship in mythology and science: ambivalence, differentiation, and the magical bond.

F AMILY RELATIONSHIPS, especially the disruptive potential of libidinal and aggressive drives within the nuclear family, are among the most common themes of mythology. The theme of twinship in mythology can be seen as the focus of real and projected psychological tensions and their imagined or preferred solutions. Mythological fascination with twins and twinship and some parallels between ancient and modern theories of personality development in twins have been reviewed by Ortmeyer. 1 We have attempted to show continuities between mythological traditions of twinship and common themes in modern research on twins. The common psychological elements in mythology, magic, and science as they deal with twinship are related to seemingly universal ambivalence and fascination with regard to multiple human births. The myths and beliefs discussed here express two kinds of ambivalence toward twinship. One is the ambivalence toward the event of twin birth itself, its implications for theories of conception and paternity, and its social and economic consequences. Another is the ambivalence in the relationship between twins that brings forth on the one hand closeness and intimacy, and on the other extreme rivalries and hostilities. Elements of either or both kinds of ambivalence are found in myths, beliefs, and customs pertaining to twins. There are also attempts at solving this ambivalence through emphasizing either the positive or negative side in the relationship. Twin birth is a challenge to primitive and infantile theories of conception and birth. Mythological theories of twin conception include the notions of double paternity or divine paternity; often these two are combined. Divine paternity puts twin birth in the category of the miraculous and mysterious, but it may also be regarded as a bad omen, being rare and therefore frightening and misunderstood. There is often a basic differentiation in mythological twinship-that of primogeniture. Because of the importance of determining the exact birth order, primacy often became a bone of contention. The disruption of the primogeniture system is one major reason for ambivalence toward the occurrence of twin birth. Another reason is economic. In primitive societies, having twins meant having two mouths to feed instead of the one that was expected. This realistic concern adds to whatever less rational fears are aroused by the occurrence of multiple births. This realistic concern about economic consequences is also the source of some ambiva-