China has implemented the etiquette of not marrying with the same surname since the Zhou Dynasty. Qu Li said: the same surname is the clan, and there is the meaning of gathering people of the whole clan, so it is based on the surname.... Even though it has been a hundred generations since their ancestors, they are still not allowed to intermarry.  Guoyu said, when you take a wife, you should avoid her with the same surname. He also said, if you don't marry with the same surname, evil doesn't come into being. From this point of view, the ancients of our country have long understood the principle of eugenics in modern genetics, otherwise they would not have realized the harmfulness of next-of-kin marriage.
The statement that the etiquette of not marrying with the same surname encourages the intermarriage of different clans, and the intermarriage of different clans promotes the integration of different ethnic groups weakens the author's explanation of unmarried with the same surname.