Xiahou Dun
Cao Song's family background is a mystery. Chen Shou wrote in the "Sanguozhi" that Cao Song's origin could not be determined. The "Cao Man Zhuan" () and the "Shiyu" (), two sources used by Pei Songzhi in his annotations to the "Sanguozhi", mentioned that Cao Song's original family name was Xiahou () and that he was an uncle of Xiahou Dun. Therefore, Cao Cao and Xiahou Dun were cousins.