Three Identical Strangers – an emotionally devastating meditation on Nature vs. Nurture

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If you can get past the annoying re-enactments, Three Identical Strangers is a fascinating and emotionally devastating documentary.  On the surface, it’s the story of three triplets separated at birth and reunited in their early 20’s.  But it resonates far and wide.

When I was younger, I very much leaned toward the Nurture side in the Nature vs. Nurture debate.  In college, I remember telling my roommate Marc that I had an aversion to bugs because — when I was a kid — I was trying to catch a grasshopper, and he ended up getting squished between my hands.

Marc’s response was, “Yes, but what were the chances that you were going to encounter a squished bug at some point in your childhood?  Probably close to 100%.  So you were going to end up hating bugs no matter what.  What about somebody who has no aversion to bugs as an adult?  Don’t you think he squished a bug at some point? His reaction to that same experience was different than yours, probably because he has different genes.”

Hmmmm….. That made me think.  It’s not quite so easy to separate out the effects of genes and environment.

Later on, I was taking a psychobiology class, and the professor said something that I’ll never forget.  “Your genes create your environment.”  He was trying to say that every organism is instructed — by its genes — to pay attention to certain things that are very important to its survival and reproduction and to pay little attention to everything else.  The simplest example of this is that human beings have evolved to only see certain wavelengths of light.  Other animals have evolved to see a different set of wavelengths.  In a way, our genes have taken a guess at which wavelengths contain the visual information that we will need to survive and reproduce.  Those are the ones we’re capable of seeing as a part of our environment.  In some real way, UV light is not even a part of my environment, because I’m incapable of detecting it.

But the interaction between genes and environment also goes in the opposite direction.  That same professor talked about certain reptiles whose eggs were sensitive to the  temperature.  At certain temperatures, the eggs would produce males, and other temperatures the eggs would produce females.  Certain genes were being turned on or off by the temperature. The environment was determining gene expression!  (Of course, you could argue that this, too, is under genetic control, and so the genes are determining how much say should be given to the environment.)

This whole line of thinking was sparked by this week’s episode of Econtalk, in which Russ Roberts interviews the Oxford psychologist Teppo Felin about the vagaries of human attention and its dependence on our goals in any situation.

Anyway, no spoilers here, but Three Identical Strangers does have something very specific to say about Nature vs. Nurture and the domains of human experience where each one might have the upper hand.

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