Nature via Nurture: Genes, experience and what makes us human. Matt Ridley
quarrelling by whom: so as they may have that well brought up by nurture, which they love so well, bequeathed them by nature…God hath provided that strength in nature, wherby he entendes no exception in nurture, for that which is in nature…Which naturall abilities, if they be not perceived, by whom they should: do condemne all such, either of ignoraunce, if they could not judge, or of negligence, if they would not seeke, what were in children, by nature emplanted, for nurture to enlarge…Which being thus, as both the truth tells the ignorant, and reading shewes the learned, we do wel then perceave by naturall men, and Philosophicall reasons, that young maidens deserve the traine: bycause they have that treasure, which belongeth unto it, bestowed on them by nature, to be bettered in them by nurture.6
He repeated the phrase in his next book Elementaries in 1582: ‘whereto nature makes him toward, but that nurture sets him forward’. Mulcaster was a curious character. Born in Carlisle, he was a distinguished scholar and famous, if strict, educational reformer. He quarrelled irascibly with the school governors and was a passionate advocate of the game of football: ‘The foteball strengtheneth and brawneth the whole body,’ he observed. Mulcaster also dabbled in drama, writing several pageants for the royal court, and educating the playwrights Thomas Kyd and Thomas Lodge at his school. He is supposed by some to have been the model for the character of Holofernes, the vain schoolmaster in Love’s Labours Lost, so there is a good chance that Shakespeare either knew Mulcaster or read him.
Shakespeare may also have been the inspiration for the next of Galton’s ideas. Two of Shakespeare’s plays turn on the confusion of twins: The Comedy of Errors and Twelfth Night. Shakespeare was himself the father of twins, and he used mistaken twins to make fiendishly ingenious plots. But, as Galton pointed out, in A Midsummer Night’s Dream Shakespeare introduced a pair of ‘virtual twins’ – unrelated individuals who had been reared together. Hermia and Helena, despite being ‘like to a double cherry, seeming parted, but yet an union in partition’,7 not only look physically unlike each other, but are attracted to different men and end up quarrelling violently.
Galton followed up the hint. The next year he wrote an article entitled ‘The history of twins, as a criterion of the relative powers of nature and nurture’. At last he had a respectable way to test the heredity hypothesis, free of the objections raised against his pedigrees. Remarkably, he deduced that there were two sorts of twin: identical twins, born from ‘two germinal spots in the same ovum’, and non-identical twins ‘each from a separate ovum’. This is not bad. For ‘germinal spot’ read nucleus and you are close to the truth. Yet in both kinds, the twins shared nurture. So if identical twins resembled each other in behaviour more than fraternal twins, then the influence of heredity was supported.
Galton wrote to 35 pairs of identical twins and 23 pairs of non-identical twins, collecting anecdotes of their similarity and difference. Triumphantly he recounted the results. Twins that resembled each other from birth remained similar throughout their lives, not only in appearance but also in ailments, personality and interests. One pair suffered severe toothache in the same tooth at the same age. Another pair bought identical sets of champagne glasses as presents for each other at the same time at different ends of the country. Twins that were born different, by contrast, grew more different as they grew older. ‘They were never alike either in body or mind, and their dissimilarity increases daily,’ said one of his respondents. ‘The external influences have been identical; they have never been separated.’ Galton sounded almost embarrassed by the strength of his conclusion: ‘There is no escape from the conclusion that nature prevails enormously over nurture…My fear is, that my evidence may seem to prove too much, and be discredited on that account, as it appears contrary to all experience that nurture should go for so little.8
SPLITTING PAIRS
With hindsight one can pick all sorts of holes in Galton’s first twin study. It was anecdotal, small, and the argument was circular: twins that appeared identical behaved identically. He had not distinguished identicals from fraternals genetically. Yet the study was remarkably persuasive. By the end of his life Galton had seen his hereditarian beliefs move from scepticism to orthodoxy. ‘Nature limits the powers of the mind as definitely as those of the body,’ said The Nation in 1892, ‘On these points, among thinkers everywhere, [Galton’s] opinions have prevailed.’9 The old empiricism of John Locke, David Hume and John Stuart Mill, whereby the mind was seen as a blank sheet of paper on which experience would write its script, had been replaced by a sort of neo-Calvinist notion of inherited individual destiny.
There are two ways to look at this development. You can damn Galton for being seduced by his ‘convenient jingle’ into presenting a false dichotomy. You can see him as one of the evil spirits of the twentieth century, cursing the three generations that followed to swinging like a pendulum between ridiculous extremes of environmental and genetic determinism. You can note with horror that from the beginning, Galton’s motives were eugenic. On the very first page of Hereditary Genius in 1869 he was already extolling the virtues of ‘judicious marriage’, lamenting the ‘degradation of human nature’ by the propagation of the unfit and invoking the ‘duty’ of the authorities to exercise power to change human nature by progressive breeding. These suggestions would grow into the pseudo-science of eugenics. With hindsight, therefore, you can blame him for an idea that would cause misery and cruelty to millions in the century to come, not just in Nazi Germany but in some of the most tolerant countries of the world.10
All this would be true, though it is a little harsh to expect that none of it would have happened without Galton, let alone that he should have foreseen where his ideas would lead. Even the convenient jingle would have soon occurred to somebody else. A more charitable reading of history would see Galton as a man far ahead of his time who hit upon a remarkable truth: that many aspects of our behaviour start within us in some way, that we are not putty in the hands of society or victims of our surroundings. You could even – though this might be stretching it – assert that this notion was vital in keeping alive the flame of liberty in the environmentalist despotisms of the twentieth century: those of Lenin, Mao and their imitators. Galton’s insights into heredity were remarkable, considering he knew nothing about genes. He would have had to wait more than a century to see that the study of twins did in the end prove much of what he had suspected. To the extent that they can be teased apart, nature prevails over one kind of (shared) nurture when it comes to defining differences in personality, intelligence and health between people within the same society. Note the caveats.
This is a recent development. Twenty years ago, the picture was very different. By the 1970s the whole notion of studying twins to learn about heredity was in eclipse. Two of the largest studies of twins since Galton were in disgrace. In Auschwitz, Josef Mengele was notoriously fascinated by twins. He sought them out among new arrivals at the concentration camp, and segregated them into special quarters for study. Ironically, this ‘favouritism’ led to a higher survival rate among twins than singletons – most of the small children who survived Auschwitz were twins. In exchange for submitting to procedures that were often brutal and sometimes fatal, they were at least better fed. All the same, few survived.11
In Britain meanwhile, the educational psychologist Cyril Burt was slowly accumulating a set of identical twins reared apart, which enabled him to calculate the heredity of intelligence. In 1966, when he published the full set of results, he claimed to have found 53 pairs of such twins. This was an extraordinarily large sample, and Burt’s conclusion that IQ was highly heritable influenced British education policy. But it later emerged that at least some of the data was almost certainly faked. The psychologist Leon Kamin noticed that the correlation had remained exactly the same, to the third decimal place, even while the data set had expanded over several decades. The Sunday Times simultaneously asserted that two of Burt’s co-authors probably did not exist (one has since reappeared, however).