Since Hugo von Hofmannsthal’s adaptation of Sophocles’ Electra in 1903, numerous dramatic versions of the Electra story have given the heroine a sexually charged relationship with her brother, or even her sister. Despite being an international phenomenon, predating Jung’s coinage of the ‘Electra complex’ by a decade and enduring through more than a century of artistic and institutional trends, this trope has received little scholarly attention. Since the appearance of sibling incest in adaptations of the Electra plays, scholars from multiple disciplines have even begun to read intimations of incest in the ancient dramatic texts. This article will consider the aetiology of a motif that resists being attributed to a single cause.