“If there is no humanity without language, nor can there be a society without parenthood. But what does it mean to be a parent?” This question from Claude Levi-Strauss is at the heart of this international and multidisciplinary study analysing the upheavals to legal family ties currently being brought about by biomedicine. As a result of the heady advances in new biomedical practices, a number of questions concerning parenthood need to be addressed. Who will be the legal father and mother of a child when infertile men and women are able to procreate? Will the child still have two parents of different sexes, or could it sometimes have three, or even four? What about the emergence of the concept of parenting and of the role of DNA testing in determining parentage? Legal experts, philosophers and sociologists from twenty countries with different cultures debated these issues, among many others, during the fifth workshop of the Réseau universitaire International de Bioéthique (RUIB – International University Network on Bioethics). Stemming from these debates, the articles brought together in this collection explore the extent to which new biomedical practices have revolutionised access to parenthood in these countries. There can be no doubt that because this topic touches on sexuality, the body and reproduction – different concepts in different cultures – one conclusion stands out: although the life sciences have now won, at least in part, control of the imparting of life, the effects of biomedicine on the legal structure of the family differs considerably from one country to the next. A rapprochement between the various systems studied would be most welcome.