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.