Alberic II, Patrician and self-styled prince of Rome, had in 936 married his stepsister Alda of Vienne, the daughter of King Hugh of Italy, and had had a son with her, Octavianus.

However, there is some doubt about this.

Benedict of Soracte recorded that Octavianus was the son of a concubine (Genuit (Alberic) ex his principem ex concubinam filium, imposuit eis nomen Octabianus), but his Latin is unclear.

If he were the son of Alda, he would have been eighteen when he became pope, and he would have been a seventh generation descendant of Charlemagne on his mother's side.

If he was the son of a concubine, he would have been somewhat older, possibly up to seven years older.

Born in the region of the Via Lata, the aristocratic quarter that was situated between the Quirinal Hill and the Campus Martius, he had been given the name of Octavianus, a clear indicator of how the family saw themselves and the future destiny of the son of Alberic.

Sometime before his death in 954, Alberic administers an oath to the Roman nobles in St. Peter's providing that the next vacancy for the papal chair would be filled by his son Octavianus, who by this stage had entered the Church.

With his father’s death, and without any opposition, he succeeds his father as Princeps of the Romans, somewhere between the ages of seventeen and twenty-four.