Since Mommsen, it has been a tenet of Roman history that Augustus transformed the ‘senatorial order’ into a hereditary class, which encompassed senators, their children, grandchildren and great-grandchildren in the male line. This paper shows that the idea of a hereditary ordo senatorius is a myth without foundation in the evidence. Augustus and his successors conferred new rights and duties upon relatives of senators, but did not change their formal rank. Moreover, the new regulations applied not to three generations of descendants, but only to persons who stood under a senator's patria potestas during his lifetime. Emperors protected the honour and property of these filii familias of senators, in order to incentivise them to participate in politics and invest their wealth into munificence. The Supplementary Material available online gives all known early imperial holders of the title clarissimus vir in the province of Africa (Supplementary Appendix 1), all known early imperial clarissimi iuuenes (Supplementary Appendix 2) and all known early imperial clarissimi pueri (Supplementary Appendix 3).