Blood is thicker than water — only half a saying
I've just learnt that the saying 'Blood is thicker than water' is taken to be the exact opposite of the full saying — which is: 'Blood of the covenant is thicker than water of the womb'. In other words the friends etc that we make are more important than the birth family.
I was always told this to STOP me putting friends or my husband over my parents.
The other one I got — a lot — was 'A son's a son until he takes a wife, but a daughter's a daughter for all of her life'. Yet when you think about it, in most religions the daughter is given to the husband. His name replaces the birth name, she would at one time have gone to live in her husband's household and so on — so surely it's the other way round and a son is a son for for all his life.