Nature, Nurture and Environment

Posted in: Comment, News and Updates

I read an article on parenting the other day as it's never too late to learn.  It only really contains this piece of advice:

“… it should be enough for us to remember that our children are human beings, worthy of the same ethical treatment we give to our friends, other relatives, and even to strangers.  So protect your children, provide for them, be good to them, and make memories with them.  Apart from that, don’t expect to have very much say in how they turn out."

Sound advice, it seems to me, even though the last sentence may well shock many people.  The article’s focus is the age-old issue of nature v nurture;  heredity v environment, and has a lot to say about twin studies – which I intend to ignore in what follows; just as I'm staying away from the vexed question of intelligence.

Reading the article took me back to 197something and a debate at the Cambridge Union where the US genetics & IQ guru, Arthur Jensen, was sub-heroically trying to argue that intelligence was X% inherited and Y% influenced by environment (ie parenting and other socialisation).  I forget the exact figures, although X > Y, of course.  It was a one-sided affair as there were six people opposing Jensen.  One was Stephen Rose; another was a bloke from the USA called Jerry Something.

I had already read enough to know that Jensen's certainties were certainly misleading, as was his spurious precision, but it was Jerry S who made the main point for me.  He said that it was obvious that intelligence was 100% inherited and 100% influenced by environment.  In other words, genetics set a limit, and parenting decided how close you got to it in your life.   This appealed to me at a common sense level.  Looking back on it, however, the very notion of a limit was far too deterministic and, well, limiting.

I held to this 100 – 100 view until a conference that I've already written about where Richard Lewontin's keynote changed this view of human intelligence and inheritance. Lewontin qualified the idea of environment to include not just parental and societal influence, but also all the influences that apply before these can begin.  These are [i] the unpredictable and varying biochemical inundation that a foetus experiences whilst in the womb; and [ii] the random, quantum-level decisions that are made, particularly in the developing brain, during development (both pre- and post-natal).  These are described in the article in this way:

"... the environment matters, but not just the environment that the child experiences in the home.  The environment in this sense is far more nebulous and hard to nail down — behavioural geneticists call it the ‘non-shared’ environment and it includes anything that causes two siblings to be different from each other.  And I really mean anything.  The psychologist Steven Pinker puts it this way: ‘A cosmic ray mutates a stretch of DNA, a neurotransmitter zigs instead of zags, the growth cone of an axon goes left instead of right, and one identical twin’s brain might gel into a slightly different configuration from the other’s.’  In other words, we should not presume that random chance plays a vanishingly small role in making us the people that we are today."

For me, that randomness might explain a lot more than why twins can be different, and is why I like this idea a lot.  It also gives something of the lie to Philip Larkin's pessimism for one thing.

Is this the end of the nature / environment debate?  I doubt it, but it's enough for me for the times being.

Posted in: Comment, News and Updates


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