The son of the Father and Mother of Ultra, brother by adoption of Ace, and first cousin of Ultraseven.

Shortly after Murena's death, his brother by adoption, Lucius Lucinius Varro Murena, was accused of conspiring with Fannius Caepio against Augustus.

His brothers by adoption include Oliver Prinz von Anhalt, Michael Prinz von Anhalt and Markus Maximilian Prinz von Anhalt.

It was a satisfaction to Augustus that Germanicus, being older than Castor, his brother by adoption, was Tiberius's natural successor, and that Germanicus's infant sons, Nero and Drusus, were his own great-grandsons.