The Subtleties of Inheritance

Half Sigma discovers “epigenetics,” which is a general term for heritable elements that are not DNA. Maternal cytoplasm is an example of an epigenetic factor, though there probably are more. I assume that epigenetics probably works to exaggerate genetic differences. For instance, if two lands are otherwise equal, except one population is “genetically” higher in intelligence, that population is less likely to experience a famine, and so less likely to be epigenetically stunted.

At the same time, (courtesy of Crooked Timber) Eric Turkheimer of CATO speaks carefully about “innate” differences. Eric post essentially boils down to the fact that genes are expressed differently in different environments. Thus, it’s possible to imagine a world, with the same DNA distribution, where sub-Saharan Africans outscore Jews on intelligence tests. And it’s even easier to imagine a system where the general factor of intelligence does not correlate with verbal skill, spatial skill, height, etc. Of course, those worlds are not our worlds.

Adam of The Metropolis Times emphasizes that, whatever average group differences are, and whatever their origins, people should be judged as individuals. And human rights belong to all humans, not just who score well on tests.

2 thoughts on “The Subtleties of Inheritance”

  1. Nice post.

    Sensitivities around issues of difference are entirely rational. The world is rife with discrimination and intolerance of all kinds. Scientific exploration is not the clean, objective process we’d like to think. And research, like the people who conduct it, is not created equal.

    It doesn’t help when we live in a country where children are told that you can be anything you put your mind to. This is the fundamental lie of access in higher education.

    We would do well to focus on the economy of individual strengths and work from there.

  2. Dan
    The Epigenome is going to open up all sorts of new ways of understanding who we are.

    Studies of twins show how the effect of how each individual experiences life shifts what genes are turned on or off – so that by 21, there is a bout a 20% difference leading in late life to more than 70%.

    So here we are two people with identical genes becoming very different.

    So what turns the genes on or off – it appears that it is our social experience. Much of the dial setting happens before we are 6.

    Nova did a neat show recently on this

    http://www.pbs.org/wgbh/nova/genes/

  3. Rob,

    “Studies of twins show how the effect of how each individual experiences life shifts what genes are turned on or off – so that by 21, there is a bout a 20% difference leading in late life to more than 70%.

    So here we are two people with identical genes becoming very different. “

    I'm not sure what you are referring to, but if you are thinking of intelligence, personality, or political orientation, the reverse is true.

    A small fraction, say 20% in variance of a population is accounted for by genes early in life. By the time individuals reach their 50s, around 80% of the variance can be explained by genes.

    That said, it's true that the more you make one factor equal (environment, maternal cytoplasm, genes), the more the other factors matter in explaining variation

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