Eugenics is the science that enables the selection of samples of a species according to certain criteria in order to increase the "quality" of this species. Eugenic practices are prohibited at the political level. However, it is possible, in the context of certain genetic diseases, or the donation of female eggs. To prevent the transmission of serious diseases or to achieve a pregnancy, the choice of an egg or embryo can be made. Eugenics is not tolerated for aesthetic or sexual choices of the future child. Bioethics ensures the proper use of this practice.