Cao Cao's father Cao Song is Cao Teng's adopted son. When Emperor Ling of the Han Dynasty was Guan Ju, The History of the Three Kingdoms recorded that Cao Cao's distant ancestor was Cao Can, the prime minister of the early Han Dynasty. Cao Jiahe Xiahou family is closely related, and Xia Houhe Cao Shi is in-laws. Later, he became Cao Teng's adopted son and changed his surname to Cao. Actually, he was Xiahou's, and He, Xia and Cao Cao were cousins.
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When Cao Cao was young, he was quick-witted, resourceful, self-willed, chivalrous, unruly and unlearned, so people at that time didn't think he had any special talents, only Qiao Xuan of Liang thought he was outstanding.
In his early years, Cao Cao showed his love and talent for martial arts, read widely and especially liked the art of war. He copied the strategies of various ancient art of war, and the book Wei Wu's Notes on Sun Tzu, which annotated the art of war, was handed down from generation to generation. These laid a solid foundation for his later military career.
References:
? Cao Cao Baidu encyclopedia