 Antonia Minor, the youngest daughter of Mark Antony and the youngest niece of Emperor Augustus, was a half-sister of Ptolemy's late mother, also a daughter of Mark Antony.Antonia Minor's mother was Octavia Minor, Mark Antony's fourth wife and the second sister of Octavian (later Augustus).Ptolemy lived in Rome until the age of 21, when he returned to the court of his aging father in Mauretania.