Anthropologists have always been aware that kinship is something more than an expression of blood ties, and this recognition explains much of the disciplines longstanding preoccupation with the topic. Although early anthropological theories assumed the biogenetic basis of kinship, over time it became increasingly difficult to sustain a distinction between the natural facts of kinship and their cultural elaboration. The anthropologists engaged with ethnographic worlds could not be fully contained by their theories and interpretations. Although attempts to rethink kinship were a feature of kinship studies throughout the twentieth century, it was the emergence of new reproductive technologies and anthropological and sociological efforts to grapple with them that were instrumental in the transformation of the field. These works revealed that kinship was not a thing-in-itself that could be studied in isolation from other aspects of society. Moreover, rather than constituting an insoluble building block out of which kinship was forged, nature was not the fixed and stable category priorly assumed.