Our understanding of what makes a person a relative has been transformed by radical changes in marriage arrangements and gender relations, and by new reproductive technologies. We can no longer take it for granted that our most fundamental social relationships are grounded in 'biology' or 'nature'. These developments have prompted anthropologists to take a fresh look at idioms of relatedness in other societies, and to review the ways in which relationships are symbolised and interpreted in our own society. Defamiliarizing some classic cases, challenging the established analytic categories of anthropology, the contributors to this innovative book focus on the boundary between the 'biological' and the 'social', and bring into question the received wisdom at the heart of the study of kinship.