Blood may be thicker than water, but that in itself does not necessarily breed happiness. Sometimes, the minds of family members can be thicker than blood*G*.
It is hard not to pass judgement, advise or even try to understand their thought processes as they wander along with you through life. So don't.
They are your basis for being and the most you should hope for is that you are there for them when they need you.
Never expect or demand retribution, just support them as they climb and catch them if they fall.