Secrecy of Origin/Incest/Medically Assisted Procreation with Anonymous Gamete Donors. “How not to Marry Him/Her?” (Essai) The practice of medically assisted reproduction and the donation of gametes and embryos have been around since the 1980’s. From this time on, the majority of countries have opted for total anonymity of the donors. The consequence is that, in every country, tens of thousands of young people are unaware of the manner through which they were conceived. One of the more obvious aspects of this situation is raised in this article : in cases where the children are aware of the circumstances of their conception, many say that they fear a chance meeting with their genitor and/or with the children of their genitor – their unknown siblings – in their daily life. The practice of attempting to erase the elements of identity connected to one’s origins raises anthropological as well as metapsychological questions, which are explored throughout this article. These issues have also raised the new and increasingly frequent practice of turning to Internet web sites devoted to helping those conceived through medically assisted procreation search for their origins.