The process of “democratisation” of the family that emerged in the late 1960s is not clear-cut. Based on a set of values embodied in the 18th century of the philosophers of the Enlightenment and on social changes on multiple levels and different times, it took nearly two centuries to make itself felt, encountering much resistance at all levels, based on a naturalistic conception of the family and society. But the shift that took place in the 1970s seems irreversible, despite the violence of social debates that it has prompted. Today relations outside of marriage, and more generally the relationships between adults, under the principle of mutual consent, are strengthening parental relationships, as reflected in the constitution of a genuine system of social parenthood at the turn the 21th century. The contradictions and inconsistencies of this democratisation of the family are becoming obvious and parentalist social management is struggling to cope with it. This article attempts to highlight the doubts and paradoxes of the issue.