A Brief Reference to Epigenetics

This is really an aside–something to tuck away for another day.

There’s a lot of discussion here about the meaning of genetics–how much it determines who we are, I suppose.   I guess that is because at least for some people, the more essential the role of genetics in determining who you are, the more important genetic parents are.   (That’s way over simplified, but will do for now.)

And in that context we’ve also talked about epigenetics.   I’m no expert (which you can tell because I am about to link to Wikipedia), but epigenetics is about the extent to which outside factors can alter the actions of genes in ways that may also determine who we are.   So once again speaking roughly, epigenetic influences undermine the arguments about the importance of genetics.

I thought of this when listening to a recent episode of Radiolab–one of my favorite podcasts.   Bear with me a bit while I explain:

In 2010 Sarah Grey gave birth to identical twin sons, Thomas and Caleb.   Identical twins are genetically identical.   But, as Sarah and her husband Ross knew from early in the pregnancy,  Thomas had anencephaly while Caleb did not.    Given his condition, Thomas could not survive more than a few days.  When he died, Sarah and Ross decided to donate his organs.   A couple of years later, the Grey’s tracked down those donations.  That’s the subject of the podcast and of this article, too.

Some researchers got some of Thomas’ cord blood as well as some of Caleb’s.   What they wanted to study was how with genetically identical twins, one could have anencephaly and the other not.   It’s pretty obvious why you might care about this.  Anyway, if you listen to the podcast, somewhere towards the last third they mention that the researchers found over 1000 (yes, that’s a thousand) epigenetic differences between the identical twins.

There’s no grand conclusion here, really.   A thousand is a big number but I’m fairly confident that most of the epigenetic differences are tiny.   On the other hand, the difference between being anencephalic and not being anencephalic is huge.   And of course, that may have nothing to do with genetics at all–that may just be environmental chance.   But it does make me think about how much we have yet to learn about what makes us who we are and how difficult it is to generalize about this.

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2 responses to “A Brief Reference to Epigenetics

  1. As you say, there is so much more to learn about both genetics and epigenetics. I worry about the (mostly egg) donor recipients who choose to simplify the impact of epigenetics in order to ‘disappear’ the donor. On a related topic but with a slightly different slant, Diane Ehrensaft writes very insightfully about the tendency of some recipients to either reduce the donor to body parts or have an illusion of a whole person where there is none, in her chapter When Baby Makes Three or Four or More: attachment, individuation and identity in assisted conception in Donor Conception for Life: Psychoanalytic Reflections on New Ways of Conceiving the Family edited by Katherine Fine. Makes for very interesting reading.

  2. Elizabeth Samuels

    The recent New York Times magazine article on two sets of identical Columbian twins mixed up at birth (and therefore raised as two sets of “fraternal twins”) is a fascinating account of genetic and environmental factors in a highly unusual case in which the separated identical twins were raised in profoundly different circumstances.
    http://www.nytimes.com/2015/07/12/magazine/the-mixed-up-brothers-of-bogota.html?_r=0

    Are there people who believe that genes have no importance and are there people who believe that environment has no importance? If not, and if it is generally accepted tha the two factors interact in very complex ,not well understood ways, then why would the degree of how “essential the role of genetics [is] in determing who you are” affect the degree of an individual’s interest in his or her genetic background?

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