Blood is thicker than water
Our loyalty to our family — that is, to our blood relations — is strong no matter how we may feel about them.
Examples from the Web for blood is thicker than water
I wonder if I can work the blood-is-thicker-than-water touch on him for a fiver afterwards?The Boy with Wings
Idioms and Phrases with blood is thicker than water
blood is thicker than water
Family ties are closer than other relationships. For example, Nancy will drop everything to help her sister; blood is thicker than water. Alluding to the fact that water evaporates without leaving a mark whereas blood leaves a stain, this proverb was first recorded about 1412.