Sun Tzu expressed a kinship and described the relationship between the father's previous generation and his next generation. And grandpa, my father's father, refers to grandpa in most parts of the country. Therefore, grandparents and grandchildren can be regarded as the same meaning. Similarly, the relationship between grandma and granddaughter is just like the relationship between grandpa and grandson, so it is also the relationship between grandma and grandpa and grandson.

Modern significance:

In modern Chinese, kinship terms can tell the identity at a glance, such as Dai (parents: uncles, uncles; Peer: brother, sister, cousin), paternal or maternal (aunt), direct or collateral (grandson, nephew), age (uncle, uncle, brother, brother) and blood relatives or in-laws (brother, sister-in-law, brother-in-law).

The Chinese kinship appellation system is complex and diverse, which strictly distinguishes lineal and collateral, blood relatives and in-laws, elders and younger generations, old and young, men and women, close relatives and distant relatives, with fine semantic function and accurate description.