Interesting that this is in The Guardian

Previous work with twins has shown that genes account for about half of the difference that is seen in IQ scores across the population, with the rest being shaped by factors such as conditions in the womb, nutrition, pollution and a person’s social environment. “Genes do not determine everything for intelligence,” said Posthuma. “There are so many other factors that affect how well someone does on an IQ test.”

Because if you published in the comment pages on the implications of this – that the tabula rasa argument is wrong, that not all can do everything – then you’d be howled down.

19 comments on “Interesting that this is in The Guardian

  1. I always suspected some malign reason for my countless failures. Something else we can blame our parents for.

  2. Charles Murray is still being vilified for saying the same thing. If anything, he put the percentage inherited at a lower value

  3. They do seem to go out of their way to minimise the finding. Suggesting that we can use brain-enhancing drugs to correct the difference; pointing out that the genes uncovered only account for 5% of IQ.

    Besides, since when have scientific facts actually made a difference to policy? Climate policy, smoking, etc. – the machine rumbles on, oblivious to reality.

  4. Every time we get one of these “scientists looked at the effects of genes on X” stories, it’s always something like 50:50. Sometimes it may be as skewed as 30:70 or 70:30, but basically it’s obvious that the correct answer to “Nature or nurture?” is “both, in roughly equal amounts”.

  5. …both, in roughly equal amounts.

    30pct inherited ability, 30pct education and training, 40pct ambition and hard work.

  6. 50:50 is an interesting ratio. But by all means. There is a genetic component to intelligence.

    Evolution means that no two populations will have equal genetic components. That is more or less a given.

    When the Guardian admits that, they will have made the real great leap forward.

  7. “30pct inherited ability, 30pct education and training, 40pct ambition and hard work.”

    The latter traits being genetic of course…………………..

  8. I could argue that the nuture component was negative. i.e. two identical children both have the capacity to score 120 IQ but one doesn’t because of poor a environment. This would still be counted as nuture being a factor as if it were positive, which leads to parents hothousing their children when all that can be achieved is the child reaching his full potential and nothing more. To put it another way, you can feed him up all you like, he still isn’t going to play professional basketball.

  9. What exactly the “nurture” bit consists of is a bit of a mystery. Much of it is probably just noise and measurement error, though as RlJ points out a mad or evil parent probably could manage to deny a child the chance of fulfilling his potential. Or malnourishment, or …..

    The % due to “nature” increases as one ages from childhood, implying that the effect of upbringing dwindles in adult life.

  10. Jim,

    The latter traits being genetic of course …

    I’m afraid I don’t agree – I would suggest memetic, not genetic.

    I hypothesise that an adopted kid (assume early so not damaged by the parents or state care) brought up in a family where education and work are seen as good things is going to (be more likely to) acquire ambition and work ethic than a kid from hard-working parents brought up, say, in a state children’s home.

    If you have evidence to the contrary, I’d be delighted to read it and, if I’m convinced, £10 to a (non-political) charity of your choice.

  11. There was a wordy commentator on the ASI called Keith Hudson who said outcomes were mostly down to epigenetics. Whatever the subject, Greek politicians being spongers, our willingness to suck landowner cock, the sorts of users of private tuition, almost anything could be explained by this thing. I still haven’t looked up what it means.

  12. Is there a genetic element to how people are brought up?

    Like, if there was no gene for intelligence, but there *was* a gene for wanting to teach your kids interesting stuff?

  13. NiV – “Like, if there was no gene for intelligence, but there *was* a gene for wanting to teach your kids interesting stuff?”

    If we were talking about an animal we would not hesitate for a second in ascribing parental involvement and parental investment to genetics.

    But somehow evolution doesn’t seem to apply to humans.

  14. Johnathan Pearce, interesting that. What struck me was the inclusion of the reduction of childhood diseases in the proposed explanations, all of which seem plausible, particularly when taken together.

  15. It’s a misunderstanding of factor analysis to think that the heritability of intelligence (or anything else) can be a constant.

    The relative important of genetic and environmental contributions depends on the variance of each in your test population.

  16. The estimated proportion of IQ variance associated with genetic factors in children is 40-60 per cent and in adults is approximately 80 per cent. The estimated proportion of IQ variance associated with shared environmental factors is relatively constant at approximately 30 per cent for ages up to 20 years but then drops to 0 per cent in adulthood. The nonshared environmental variance is relatively constant and close to 20 per cent. The upshot of this is that education and other social factors have zero effect on adult intelligence.

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