Studying the evolution of knowledge on infancy reveals links with, on the one hand, the conceptions of parenthood and, on the other hand, the technical, social, political, and ideological changes, as well as the changing standards of moral behavior. Since World War II, several abrupt changes—be they epistemological political, or social—have marked this evolution. The emergence of the theory of hospitalism and of emotional deprivation, due to the damage caused by placing babies deprived of their parents in special institutions, marks the appearance of psychoanalysis in pediatrics through child psychiatry. From now on, it will become impossible to ignore the importance of the affective dimension for the baby. However, this importance creates an overestimation concerning the relationship between mother and child, which is used to delegitimize collective child care, as well as to marginalize the fathers. Not until the late 1960s and the protest movements was this excessive maternal preeminence gradually called into question and collective child care and the presence of other children along with paternal competence brought back into favor. The latter asserts itself, from the 1980s onward, in the publications of clinicians and developmental psychologists. This was precisely the time when artificial insemination introduced deep changes and caused us to reexamine the issue of filiation. At the end of this evolution, the image of the child, which is based on social research and popularized by the media, is that of a totally fulfilled and successful child who is decisive and vulnerable. This image raises questions about the conception of personhood our society holds.