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 Younger Drusilla and Julia Livilla. Agrippina's two elder brothers and her mother were victims of the intrigues of the Praetorian Prefect Lucius Aelius Sejanus. She was the namesake of her mother. Agrippina the Elder was remembered as a modest and heroic matron, who was the second daughter and fourth child of Julia the Elder and the statesman Marcus Vipsanius Agrippa. The father of Julia the Elder was the Emperor Augustus, and Julia was his only natural child from his second marriage to Scribonia, who had close blood relations with Pompey the Great and Lucius Cornelius Sulla. Maternally, Agrippina descended directly from