Who is bad for the son-in-law's grave: her family.
Not from my own family.
In fact, the daughter and son-in-law are husband and wife, and they naturally blend in. Therefore, the taboo of going to the grave for daughter and son-in-law is actually similar, but the customs will be different everywhere. In some places, daughters are not family members, so it is not appropriate to go to the grave, and so is the son-in-law.
Affect sb.' s fate
Some areas will think that the son-in-law is actually not his own family, so it is disrespectful to go to the grave, just as unmarried daughters in some areas can go to worship their ancestors, but if married daughters go to worship their ancestors, it will be bad for the family's fortune and reputation, and will affect the family's fortune. Outsiders will think that the family has no successor.
What are the taboos?
Burn all the paper money.
Generally speaking, the biggest taboo when burning a fire is that it is not finished, so that ancestors can't receive the paper money they burned at all, which is equivalent to doing nothing, and if they leave while there are still some flames, it is easy to cause a fire. Generally speaking, we'd better burn paper money before noon 12.
Too young children can't go.
No matter where the customs are, there is a taboo that is the same, that is, no matter whether it is a boy or a girl, if she is too young, she is not suitable for going to the grave. Generally speaking, if a child is under six years old, it is not suitable for both men and women to let him participate in ancestor worship activities. Because the child is too young, the yang is low, and the cemetery is a place with heavy yin, it is easy for the child to see some unclean things, and it is easy to cause some negative substances to wrap around the child, which leads to the child's frequent illness and so on.