The Frontal Cortex

Nature, Nurture and Switched Babies

Once upon a time, back when the Human Genome Project threatened to unravel the mystery of human nature – every aspect of individuality would be reduced to a SNIP – the Nature/Nurture debate seemed like the most hotly contested question in science. Are personality traits inherited or learned? To what extent can we rebel against our nature? How free are we?

Those questions now seem rather obsolete. They were rooted, after all, in a false dichotomy. Here is how I summarized this new understanding in my book:

What makes us human, and what makes each of us our own human, is not simply the genes we have buried in our base pairs, but how our cells, in dialogue with our environment, feedback onto our DNA, changing the way we read ourselves. Life is a dialectic. For example, the code sequence GTAAGT can either be translated as instructions for the amino acids valine and serine; or it can be read as a “spacer”, a genetic pause that keeps other protein parts an appropriate distance from each other; or it can be read as a signal to cut the transcript. Our DNA is defined by its multiplicity of possible meanings; it is a code that requires context.

That said, every once in a while you run across a story that reminds you just how powerful Nature really is. A few weeks ago, This American Life devoted its full hour to the powerful tale of two babies from the same Wisconsin town that were switched at birth. (It turns out that one of the mothers knew about the switch after a few weeks, but didn’t say anything for more than forty years.) While the soap opera itself is riveting – how would you feel after learning that your mom isn’t really your mom? – the show is also a testament to the disconcerting reach of genetics. It turns out that the two switched women closely resemble, both in appearance and temperament, their previously unknown biological families. While one family was fun-loving and playful, and gave birth to a daughter that would also grow up to be fun-loving and playful (even though she never knew these parents), the other family was extremely religious, and gave birth to a daughter who also grew up to extremely religious, even though she never knew that her biological father was an evangelical preacher. The list of parallels goes on and on. It’s a rather spooky tale, and although it’s certainly an extreme example of genetics at work, it’s still a useful reminder that who we are is partially beyond our control.


  1. #1 Roberto
    August 26, 2008

    please remind me: what is the point in this story?

  2. #2 Luci
    August 26, 2008

    Lots of people must have the gene that switches for a staunch refusal to be limited to a mere dual choice. Mind or Brain. Nature or Nurture. Paper or Plastic. Descartes was wrong. I use cloth bags. Nature and Nurture are just the loudest members of the behavior gang. What’s the receptor for variety and surprise that keeps our cells happy to be alive?

    As with the choreography of swirling neurochemicals, intercranial lightning bolts, the whole alphabet of waves and all those squishy pink gray blobs, let’s not be so straight and limiting in our quest to name and codify what the heck makes us who we are. Neuroscience is as essential as mother’s milk. Knowledge is brain food, and it’s an always varied and delicious experience to be savored (that whole umami thing). But maybe we’ll never taste the ultimate morsel. The quest is perhaps enough. We get intiguing answers out of the labs at BIDMC, and also out of your local symphony hall, blues club, favorite book store, and from the posted artwork at the kindergarten.

    My teenage niece who looks and sounds like her mother has this explanation when she answers the phone – Mom and I sound alike, but, you know, we don’t say things the same way. Syntax and context.

    (so coincidentally the Stranglers song ‘Genetix’ is on the stereo at this exact moment.)

  3. #3 Brian Schmidt
    August 26, 2008

    Interesting story. Not randomly selected tho – the show was looking for something that worked on radio. “Kid just like adoptive parents” isn’t all that exciting.

  4. #4 qetzal
    August 26, 2008

    It’s a rather spooky tale, and although it’s certainly an extreme example of genetics at work, it’s still a useful reminder that who we are is partially beyond our control.

    I don’t agree it’s certainly genetics at work. It may be genetics at work, but as Brian Schmidt notes, it may simply be selection bias.

    How many times have babies been switched at birth and grew up to be just like their ‘adoptive’ families?

  5. #5 OftenWrongTed
    August 26, 2008

    Some remarkable similarities have been written about individually adopted twins who were reunited after being raised apart from each other.

  6. #6 Rachael
    August 26, 2008

    Roberto, I believe that the “point” is simply to be thought provoking. I do not believe that interesting observation needs to take the form of a compelling argument.

    Stories like this are humbling for so many reasons. First, “I think I’ve got problems”, ha : ) Second, we know so little. I do not believe in a creator, but I am humbled by the complexity of these processes which we’d like to think we understand. I would be very bored and very sad if the day ever came that interesting occurrences like this were predictable.

    Anyway, I agree that the story does not prove anything one or another, but it is interesting nonetheless

  7. #7 Roberto
    August 26, 2008

    rachael, that was precisely my point. Regardless we thank god or not for evolution, for ones-or creation-for anothers, we all “got problems”. Let me humbly invite you to predict that being able to predict anything at all about the essence of human nature is unpredictable, for now.

  8. #8 Alan
    August 26, 2008


    It would have been better to say this than to ask a question as if you were expecting a point. This said, Lehrer himself prefaced his post saying that nature vs. nurture is a false dichotomy.

    What I think is a better question to ask is whether the daughter who grew up to be extremely religious is more tolerant of the fun and playfulness of the family she grew up in, or whether she rebelled against it. If she had not be switched and instead grew up with her biological family, what would have been her orthodoxy?

    And then: How much does our acceptance of other people depends not just on our exposure to them (such as peaceful interracial neighborhoods), but also the degree to which our genes might predispose us to accept differences in others?

    How much then do our genes cause us to create varied social norms that we use to identify people that are members of our group, and pick out and bully people who don’t conform? (The us against them dichotomy.)

  9. #9 Roberto
    August 27, 2008

    Alan : Mr Lehrer was not very clear where was he going. I didnt see the point but I was expecting one. It is very likely there is a robust “not like-me-us” biomechanism, but is also very likely this system is very malleable. The evolutionary constrains and forces of the ‘checks and balances” of self interest, altruism and cooperation, in-group and out group are obviously hard to “categorize’, but I see no evidence that behaviour, attitudes and derived social norms are cast in the stone of our genes.

  10. #10 shannon murphy
    September 1, 2008

    Roberto: Mr. Lehrer was very clear about where he was going, and very clear when he got there. The point was that “who we are is partially beyond our control.” How about you try to be constructive–write your own blog post about what you’re interested in, rather than tearing down someone else’s because his point (and, again, he made a valid and interesting point) was not exactly what you wanted to hear. Sheeesh.

  11. #11 jb
    September 1, 2008

    For the record: one presumably has a choice in picking your DNA as a much as one has a choice in aspects of life, at least according to the Tibetan Book of the Dead. There it is described how, after a review of the life you just had, you pick your parents in union. Not something that is testable by our experience.
    However there is a general testable theory about making choices that goes back to a picture that the Buddha is said to have drawn in the sand. It is summarized in a teaching image called the Bhavacakra or Wheel of Being. Unfortunately there is not a good book on this teaching though you will read of it in many Buddhist texts. The Wikipedia article on ‘bhava cakra’ is a good start. There you can see how one can go from one emotional state to another during the day as one one makes one ego-confirming choice after another and consequently one is happy for awhile(the god realm) and then angry (the hell realm) when whatever makes you happy is taken away/dissovles/ends. Or it can be read as how one gets from one liftime to the next.

  12. #12 Roberto
    September 2, 2008

    Shannon Murphy, you think the point was made, I dont, because there wasnt one. “Who we are is partially beyond our control” is ancient history. And, what was his story morals? That there it can be a genetic bias in who we are. Sheeeess. (what does this mean?) If you get emotional partially beyond control about different opinions maybe you can start a blog for non-dissenters of so blogger, in which case you have a cult and not a blog. Sheeess..

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