near Rome. He was the only son of 12, by Gnaeus Domitius Ahenobarbus and second and third cousin Agrippina the Younger , sister of emperor Caligula . Lucius' father was the grandson of Gnaeus Domitius Ahenobarbus and Aemilia Lepida through their son Lucius Domitius Ahenobarbus . Gnaeus was a grandson to