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.
Emperor Kang of Jin empress. Later in 343, Emperor Kang's other uncle, Yu Yi (庾翼), proposed a major military campaign against Later Zhao, in coordination with Former Yan's ruler Murong Huang and Former Liang's ruler Zhang Jun, both nominal Jin vassals. Most officials feared this large undertaking, but with support from Yu Bing, Huan Wen (Emperor Kang's brother-in-law, having married his sister Sima Xingnan (司馬興男) the Princess Nankang), and Sima Wuji (司馬無忌) the Prince of Qiao, Emperor Kang approved the plan and mobilized troops. Yu Bing was made a governor to coordinate with Yu Yi, and He Chong was recalled to replace him, and