The saying "son-in-law should not go to the grave, go to the grave to insult the ancestors" reveals the unique position of the son-in-law in the family, even if it is a kinship, the son-in-law cannot integrate into the father-in-law's family, this phenomenon has three reasons.
First, the son-in-law is not a member of the father-in-law's family, and it is against the etiquette system to go to the grave.
In ancient times, people adhered to a patriarchal system based on blood ties, and men inherited the family business of their ancestors. Women play the role of connecting the powerful in marriage. Historically, there have been examples of similar ** marriages, but even so, the son-in-law is still considered an outsider in the father-in-law's family. In peacetime, even if the son-in-law has a close relationship with the father-in-law, he will not be allowed to sacrifice to the ancestors in order to follow the rituals and maintain the lineage.
Second, the son-in-law's participation in ancestor worship activities may destroy the fortune of the clan.
In ancient agrarian societies, people relied on nature for their lives, and in order to unite against various risks, the concept of clans was formed. People with the same surname build ancestral halls and regularly worship their ancestors to pray for the prosperity of their families. When a son-in-law steps into the ancestral hall or ancestral tomb of his father-in-law's house, it may have a negative impact on feng shui and damage the fortune of the clan.
Third, the purpose of not allowing his son-in-law to go to the grave is to protect his image.
The son-in-law also has his own family, and participating in the father-in-law's ancestor worship activities may be seen as a betrayal of the ancestors, causing reproach and ostracism from the same clan. The father-in-law avoided his son-in-law from participating in ancestor worship, also to protect his face and let him have an explanation in the family, especially considering that the situation of the son-in-law may not be easy, and the daughter may also be implicated because of this.
It is worth noting that the male who is involved in the family, i.e. the son-in-law, can be considered an exception. Historically, it was a cultural phenomenon that men were sometimes reused and funded. In this case, the son-in-law may be considered part of the family and allowed to participate in ancestor worship.
The patriarchal system is a product of the feudal era, and with the development of society, people's values and concepts of marriage have also changed. Nowadays, people pay more attention to social relationships, and the status of sons-in-law in the family is gradually rising, sometimes even regarded as "half a son", and in some places, sons-in-law are specially invited to participate in ancestral worship activities to show the prosperity of the family and the emergence of talents.