What are the implications of microchimerism in sociocultural and ethico-legal contexts, particularly as they relate to the destabilization of genetic origins? Conventional biomedicine and related law have been reluctant to acknowledge microchimerism—the existence of unassimilated traces of genetic material that result in some cells in the body coding differently from the dominant DNA—despite it becoming increasingly evident that microchimerism is ubiquitous in the human population. One exception is maternal–fetal microchimerism which has long been recognized, albeit with little consideration of the (...) nonmedical implications. Most immediate issues concern the ongoing biomedical debate around whether microchimerism is beneficial in terms of enhancing the body’s range of immunological responses, harmful in provoking autoimmune diseases, or simply neutral with respect to subsequent health. That controversy remains unresolved, but whichever way it develops, I want to extend consideration by insisting that changing biological concerns cannot be separated from sociocultural and ethico-legal effects. Once the diversity of DNA coding in a singular body has been established, relations of kinship, the identification of legal parenthood, and the operation of surrogacy laws are of direct interest. The overriding problematic asks whether our ethical and legal apparatus is able to address such newly emerging questions. (shrink)