28 September is celebrated as Daughter’s Day. Happy Daughters Day to all the Daughters, though it is little belated .

A son is a son till he gets a wife, but a daughter is daughter for life.

Any answers for the few questions that I have.
1) What causes this to become true?
2) Why do sons change whereas daughters don’t?
3) What changes occur in a daughter when she becomes a DIL ?
4) What changes occur in a son when he becomes someone’s husband?
5) Why does a daughter when she becomes a DIL want her husband just to remain her husband and cease to be a son?
6) Why can’t many Inlaws treat their DIL as their daughters?
7) Why can’t DIL treat her Inlaws as her own family?

Will be glad to know your views on this.