“Blood is Thicker Than Water.” Really?

“Blood is thicker than water.”

People trot out this 400-year old platitude whenever they want to justify acting according to the obviously illusory cognitive bias of preferring to help those they are related to. Biology dictates, for apparent enough evolutionary reasons, that we help those in our tribe, and that we define our tribe on familial grounds.

Nonetheless, biology does not determine what is right.

I must confess my bias at the outset. I am one of five children. Of my four siblings, I have a step-brother, a half-sister, a full-sister and a step-sister. No two have the same biological familial relationship with me. They are all my real siblings.

I adore my family. Nonetheless, we did not have so idyllic a household that I don’t understand why Hugh Kingsmill once said that “friends are God’s apology for relations.”

I was once asked, “If you were standing at the edge of a frozen lake, and you saw a human stranger fall in and your dog fall in simultaneously, which one would you save if you could only save one?” I’m inclined to say I would save my dog. But, I by no means define what is real and what is right by my own intuitions, and neither should anyone else.

The intuition that members of our family, particularly members of our genetic nuclear family, are more important than other people just because they are related to us is a bald and unconvincing fallacy. What’s more, it’s a fallacy that we can overcome.

I’m all the evidence one could need. My brother and I share no blood. My older sister and I share all of our blood (read: we have the same two parents). In a house with five children born of at least 3 different combinations of parents, I think that I am just as genuinely related to each of those two people, one by water and one by blood.

The broader point, and the reason I am taking the time to take this proverb apart, is that all it really does is to affirm the oldest and most pernicious belief in human history: that there is something inherent about oneself which is superior to everyone else. That you are inexorably a member of a faction, and that what is good is what is good for that faction.

People who believe that blood is thicker than water seem determined to test it by shedding as much blood as possible.

For this belief my parents housed me, but for this belief the Zealots died at Masada. For this belief we feel safe walking at night in our home city than in a foreign place, but for this belief the British yolked the Indian people for 89 years. I could go on. 

The belief that it matters that blood is thicker than water is a hangover from history. Family is only important insofar as members of your family are also your friends. For the same reason that we reject hereditary monarchy, that the accident of birth does not really matter, we should reject this advice out of hand. 

Character matters. Experiences matter. Bonds and intimacy and closeness and friendship matter. It is wonderful that often these things exist within a family. Biology, however, doesn’t matter at all.

I can sympathize with the mighty Stephen Fry, who, while touring a Mormom temple, was told that in the Mormon faith, the afterlife held the promise of an eternity with all of your family. He replied: “And where do you go if you’re good?”

So, the next time you hear somebody appeal to this petty, preposterous anachronism, join me in righteously turning up your nose.