For several decades, molecular genetics have given rise to a new order of phenomena, profoundly disturbing the classic ideas that men have of their identity and their place in the universe. What becomes of the classic figure of man when hybridizations permit the systematic crossing of the frontiers between species? What do the possibilities opened by cloning and especially the grafting of foreign genes in mammals mean to us? What happens to the classic structures of relationship when the introduction of (...) foreign genes into the cells of embryos allows us to obtain individuals that are heirs of the genetic patrimony of eight or twelve different parents? The list of all these strange phenomena would be long, and the disquieting nature of the results thus obtained gives spectacular effects that, for the scientific mind, are not satisfactory. It is thus in a different perspective that we must reflect on the rapid irruption of this new order of phenomenality brought about through the genetic approach. (shrink)