Incest of unequal gravity: the "incestus iuris gentium," which was applied to both Romans and non-Romans in the Empire, and the "incestus iuris civilis," which concerned only Roman citizens. Therefore, for example, an Egyptian could marry an aunt, but a Roman could not. Despite the act of incest being unacceptable within the Roman Empire, Roman Emperor Caligula is rumored to have had sexual relationships with all three of his sisters (Julia Livilla, Drusilla, and Agrippina the Younger). Emperor Claudius, after executing his previous wife, married his brother's daughter Agrippina the Younger, and changed the law to allow an otherwise illegal union.
Agrippina the Elder Caesar, Tiberius Julius Caesar, a child of unknown name (normally referenced as "Ignotus"), Gaius the Elder, the Emperor Caligula (Gaius the Younger), the empress Agrippina the Younger, Julia Drusilla, and Julia Livilla. Only six of his children came of age; Tiberius and the Ignotus died as infants, and Gaius the Elder in his early childhood. Her husband's career in the military began in AD 6, with the Batonian War in Pannonia and Dalmatia. Throughout Germanicus' military career, Agrippina is known to have traveled with her husband and their children. Germanicus' career advanced steadily as he advanced in ranks following the