He was born circa 578 BC.
Most Roman sources name Servius' mother as Ocrisia, a young noblewoman taken at the Roman siege of Corniculum and brought to Rome, either pregnant by her husband, who was killed at the siege: or as a virgin. She was given to Tanaquil, wife of king Tarquinius, and though slave, was treated with the respect due her former status. In one variant, she became wife to a noble client of Tarquinius. In others, she served the domestic rites of the royal hearth as a Vestal Virgin, and on one such occasion, having damped the hearth flames with a sacrificial offering, she was penetrated by a disembodied phallus that rose from the hearth. According to Tanaquil, this was a divine manifestation, either of the household Lar or Vulcan himself. Thus Servius was divinely fathered and already destined for greatness, despite his mother's servile status; for the time being, Tanaquil and Ocrisia kept this a secret.
Servius' birth to a slave of the royal household made him part of Tarquin's extended familia.