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.
Otto IV, Holy Roman Emperor castle on 19 May 1218, requesting that he be mortally expiated in atonement of his sins. Historian Kantorowicz described the death as "gruesome": "deposed, dethroned, he was flung full length on the ground by the Abbot, confessing his sins, while the reluctant priests beat him bloodily to death. Such was the end of the first and last Welf Emperor." He is entombed in Brunswick Cathedral. Otto was related to every other King of Germany. He married twice: He had no children by either Beatrice or Marie. Otto IV, Holy Roman Emperor Otto IV (1175 – 19 May 1218) was one