Claudia Marcella
Messalina was the daughter of Domitia Lepida the Younger and her first cousin Marcus Valerius Messalla Barbatus. Her mother was the youngest child of the consul Lucius Domitius Ahenobarbus and Antonia Major. Her mother's brother, Gnaeus Domitius Ahenobarbus, had been the first husband of the future Empress Agrippina the Younger and the biological father of the future Emperor Nero, making Nero Messalina's first cousin despite a seventeen-year age difference. Messalina's grandmothers Claudia Marcella the Younger and Antonia the Elder were half sisters. Claudia Marcella Minor, Messalina's paternal grandmother, was the daughter of Augustus' sister Octavia the Younger. Antonia Major, Messalina's maternal grandmother, was the elder daughter of Octavia by her marriage to Mark Antony, and was Claudius' maternal aunt. There was, therefore, a large amount of inbreeding in the family.