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Plomin's book is written in a practical, down to earth style. It's not at all academic. The big ideas (relentlessly hammered home) are these.
- All traits (physical and psychological) have a substantial genetic component. Heritability is around 50% as a rule of thumb. Higher for traits like height, weight and intelligence.
- Shared environments such as the family and school do not significantly affect traits. Schools don't make you smarter and parents don't make you nicer.
- Schools will educate you to your potential aptitude if they're any good (and may socialise you into an elite). Bad parenting can damage a child. But absent active damage, it's the child's inherited genetics which determine performance and personal outcomes.
- Non-genetic influences on traits are the generally random effects of life events and short lasting (these include test imprecision).
- Apparent environmental differences (eg parents who read to their children in a house full of books as against ...) have a substantial genetic component (studious parents have studious children). Plomin describes this as nature in nurture.
Strong claims, but based on vast experiments with hundreds of thousands of participants. The results strongly replicate. Problem is, they're quite counterintuitive and few people believe them.
Toby Young writes in Quillette about a recent debate in London:
"On Monday in London’s Emmanuel Centre a debate took place that pitted two Quillette contributors - Robert Plomin and Stuart Ritchie - against two “experts” on child psychology - Susan Pawlby and Ann Pleshette Murphy. The motion was “Parenting doesn’t matter (or not as much as you think)” ...Young describes the debate in detail and then describes the results:
The ushers asked people to vote for or against the motion on their way in and then again at the end, the idea being that the “winners” would be the side that persuaded the most people to change their minds rather than the side that got the most votes. Which was just as well for Plomin and Ritchie since only 17 percent agreed with them at the beginning of the evening, with 66 percent against and 17 percent saying “Don’t Know.”
"The debate was well-chaired by Xand van Tulleken, a doctor and broadcaster who has an identical twin brother named Chris, and, after he’d taken plenty of questions and done his best to sum up, the audience was asked to vote again.Few people truly believe scientific abstractions until the engineering stares them in the face. But that could happen, given the falling cost of whole genome sequencing together with ever larger scale Genome-Wide Association Studies (GWAS) for every trait imaginable.
As expected, a majority still disagreed with the motion, but Plomin and Ritchie had succeeded in persuading some people to change their minds. The number against the motion declined from 66 percent to 51 percent, while those in favor increased from 17 percent to 29 percent, with 20 percent saying “Don’t Know.”
That made Plomin and Ritchie the winners."
Soon anyone's genome will be cheaply sequenced and their polygenic scores read off (at any age including infancy, in utero or for IVF selection) to deliver personalised results for a palette of physical, psychological and aptitude life-traits.
Already there are the early signs that the liberal media, the op-ed writers and professional pundits are beginning to warm to the idea. Plomin seems to have avoided the public evisceration he was undoubtedly fearing.
The book is interesting, important and enlightening. One of the books of the year.
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Eric Turkheimer on his blog is complaining that Plomin has used his ideas without attribution. This may be true but he should get over it: this is popularisation, not academia. If the reception had been super-hostile, Turkheimer might now be experiencing relief rather than angst.
Turkheimer is not alone, by the way. Few of Plomin's peers get namechecked. There could be a few more bruised egos out there.
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James Thompson of UCL has an excellent and detailed chapter-by-chapter review and Greg Cochran wrote a review at Quillette, "Forget Nature Versus Nurture. Nature Has Won".
Worth checking both out.
One notable absence in this summary is "epigenetics". Modern accounts, of at least medical heritability, should include references to epigenetics I think. I don't know (perhaps it isn't known yet) whether learning/behaviour has epigenetic components, as opposed to genetic (plus nurture) ones.
ReplyDeleteI get the impression that epigenetic inheritance can be more local to one's environment, whereas genetic inheritance is more long term connected with the history of the species. There is even talk of a hypothetical "epigenetic code" in WP.
Is epigenetics in this book?
Yes, epigenetics is mentioned in the book. It turns things off rather than adding de novo information. It's a mechanism of small effect, typically over-hyped by those with a nurturist agenda.
DeleteI also didn't mention a substantial discussion of mental disorders which are reframed as multi-sigma outliers within the (normal) population distribution of genomic variation. This is (will be) important for psychiatry.
I have put it on Library order, though there is a queue.
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