The full quote "blood is thicker than water" is actually a misquotation. The complete proverb, from which the common phrase is derived, is "The blood of the covenant is thicker than the water of the womb."
This complete proverb emphasizes the strength of bonds formed through shared experiences and agreements (the "covenant") over the bonds of family (the "water of the womb"). The commonly used phrase, "blood is thicker than water," takes the proverb out of context and reverses its intended meaning. It implies that family ties are always stronger than other relationships, which isn't the sentiment expressed in the complete proverb.
Therefore, while "blood is thicker than water" is widely known, it's crucial to understand its origins and the truer meaning conveyed by the full proverb: "The blood of the covenant is thicker than the water of the womb."