Why is the concept of the older generation "raising children to prevent old age"?

The older generation always has the concept of preferring sons to daughters, because they think that if they have daughters, they will eventually have to raise them for others. Why do they have such an idea?

First of all, they think that with a son, the child can truly belong to his own family, because the son will marry a daughter-in-law, but marrying a daughter-in-law is to come to his own home, not to go to someone else's home by himself. So at this time, he thinks that only the son is truly biological, and the man has a higher position in the previous family status. It can be said that everything in the family depends on the man, so the family also feels that it is more reliable to have a son.

Secondly, as we all know, after a child is born, it usually takes the father's surname, so if a daughter is born, the daughter's child will take the other's surname, so many people think it is a last resort, which is why many families didn't like their daughters at that time. In addition, my daughter will marry someone else when she grows up, which means she will go to someone else's house when she grows up and take care of someone else's house in the future. If she wants to mind other people's business, she will no longer be a member of her own family. There is an old saying that married daughters throw out water, so the older generation of parents think so, thinking that their daughters are not a member of their own family when they marry.

In fact, these are relatively feudal concepts. As far as family positioning is concerned, both husband and wife are equal now. No matter how big or small things are at home, two people need to discuss them, and no one can decide everything, so there is no one who listens to whom and who doesn't listen to whom. Secondly, even if the daughter gets married, she will only form an independent small family to take care of both parents, not just the man's parents, so the daughter and son should be the same. Fortunately, however, there is less feudal thought of protecting the elderly by favoring boys over girls. Now everyone thinks that boys and girls are the same, so this has never happened again.