SARAH DITUM

The Mail on Sunday - Event - - BOOKS -

Imag­ine if you could tell the fu­ture. Dis­eases, de­pres­sion, ed­u­ca­tional achieve­ment, even di­vorces – all could be un­rolled from a sim­ple, cheap test con­ducted on new­borns. That, at any rate, is the big prom­ise of psy­chol­o­gist Robert Plomin’s book, based on ex­ten­sive re­search into the ge­netic ba­sis of our per­son­al­i­ties. Our DNA, he says, can be a ‘for­tune-teller’. Thanks to re­cent break­throughs in genome anal­y­sis, claims Plomin, it is no longer a ques­tion of whether our genes have this pre­dic­tive power, but of when it will be har­nessed. The DNA rev­o­lu­tion is here and can­not be un­done.

The metaphor of the blue­print is a com­pelling one. It’s also mis­lead­ing, which means Plomin spends half his time ad­vanc­ing the idea that our genes are ev­ery­thing, and half awk­wardly try­ing to tem­per the over­state­ment. In­her­i­tance ac­counts for, on av­er­age, about 50 per cent of all our per­son­al­ity traits. That’s a hefty enough fig­ure to throw doubt on any as­sump­tion that nur­ture bests na­ture, es­pe­cially given Plomin’s ar­gu­ment that a lot of what we call ‘nur­ture’ is tied up with ‘na­ture’: be­cause chil­dren take af­ter their par­ents, for ex­am­ple, the home en­vi­ron­ment is likely to be a close re­flec­tion of the child’s ap­ti­tudes.

But if your ge­netic in­her­i­tance has given you a flair for num­bers, you might no­tice that 50 per cent is still some way shy of 100. You can’t draw an ac­cu­rate por­trait of the adult hu­man be­ing sim­ply by un­rav­el­ling his or her dou­ble he­lix. That’s some­thing that Plomin stresses later in the book, us­ing him­self as an ex­am­ple: al­though he has a high ge­netic propen­sity for obe­sity, he is only mod­er­ately over­weight, and he cred­its his knowl­edge of his DNA with re­in­forc­ing his willpower. Un­for­tu­nately, few read­ers are likely to get that far into Blue­print, stodg­ily writ­ten as it is.

Be­cause we don’t yet un­der­stand the mech­a­nism by which DNA de­vel­ops into par­tic­u­lar traits, the book can’t ful­fil its sub­ti­tle’s prom­ise of ex­plain­ing ‘how DNA makes us who we are’. In­stead, we get a litany of prob­a­bil­i­ties.

And de­spite Plomin’s in­sis­tence that fears about eu­gen­ics are mis­placed, it’s easy to see how an un­sub­tle in­ter­pre­ta­tion of his con­clu­sions will feed fa­tal­ism about so­cial out­comes. To his credit, he is keen to start a wider con­ver­sa­tion, say­ing: ‘Ge­net­ics is much too im­por­tant to leave to ge­neti­cists alone.’

On the ba­sis of this dull book, it must be con­cluded that it’s also much too in­ter­est­ing a dis­cus­sion to be left to ge­neti­cists.

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