 "Nero" was a traditional cognomen (third name) of the Claudii, whereas "Drusus" was given to a branch of the "gens Livia".Using a cognomen such as "Nero" as a first name was unusual, as was the prominence given to his maternal lineage in adopting "Drusus" as his cognomen.Drusus was raised in Claudius Nero's house with his brother, the future emperor Tiberius, until his legal father's death.