One reason why research into racial differences in intelligence and cognition is regarded as tainted and undesirable

A huge scientific scandal in the mid-twentieth century served to discourage any objective study into inherited intelligence

We are often assured that no serious research into the inheritance of intelligence shows any correlation between ethnicity or race and intelligence. This is quite true, but more than a little misleading. No research has shown such a connection because nobody for the last fifty years has dared to conduct a proper, large-scale study of the subject. The very idea that most intelligence is inherited, rather than acquired as a result of influences of upbringing and environmental factors is viewed as a dangerous and best avoided.

The idea that human intelligence is largely inherited has always been tangled up with the belief that black people were more likely to be of very low intelligence and unlikely to be of high intelligence, compared to white people. If intelligence was just another inherited characteristic, like skin colour or height, then the conclusion was inescapable. If two people with low IQs had a child, then their child would probably have a low IQ as well. The chances that such a child would, even with the best upbringing and education, turn out to be a genius, were vanishingly small. Since the IQs of black people, when measured, tended to be a good deal lower than the average white person, about 15 points, it followed inexorably that their children would be dull-witted and all the schooling in the world was not going to change that. This idea had a strong bearing on any discussions about race and education up to the 1970s, by which time it was beginning to be described as ‘racist’ in the pejorative sense that it indicated prejudice and unfavourable treatment of black people.

     Cyril Burt was an educational psychologist with the London County Council in the 1920s. He was an enthusiastic exponent both of the idea that intelligence was almost completely hereditary and also of the need to prevent people with low IQs from having babies together. Part of his job entailed identifying children in London schools who were, as the term then was, ‘feeble minded’. These were often sent off to residential institutions, where the sexes were kept entirely separate. For some, these homes would be where they would spend the rest of their lives. By ensuring that males and females could not mingle freely, there would be no chance of girls getting pregnant and giving birth to babies who would themselves be ‘feeble minded’. If this sounds like a form of eugenics, that is because it is precisely what it was. Burt was keen on breeding out ‘mental deficiency’ and because he was convinced that intelligence was passed on to children in a similar way, and according to the same rules, as skin colour and height, he thought that isolating those with very low IQs and forbidding them to have babies was a sensible and humane course of action for society to take.

     In 1931, Cyril Burt was appointed Professor and Chair of Psychology at University College London. He had a great influence on the 1944 Education Act and the change in British education which began after the end of the Second World War. Burt was knighted in 1946 for his services to psychology and the development tests for intelligence. It is impossible to overstate the influence which this man had upon the field of psychology and beliefs about the nature of intelligence, not just in Britain, but throughout the entire world. His former students went off into professional life without the shadow of a doubt that the professor had demonstrated that at least 85 % of a person’s intelligence was inherited from his or her parents and that there was nothing which any amount of education could do to alter this. The British school system from the late 1940s onward was also predicated on this assumption. Children were tested for intelligence at the age of 11 and then allocated to either an academic grammar school or to a vocationally geared Secondary Modern, where the emphasis was on practical subjects rather than anything too cerebral. It was expected that those consigned to Secondary Moderns would end up as labourers or in jobs which required little in the way of abstract thought.

      The relevance of this to race and intelligence will be immediately apparent. The twin pillars of Cyril Burt’s work were firstly that it was possible accurately to measure intelligence and secondly that this intelligence was almost entirely handed down genetically. Since the testing of black people’s intelligence invariably indicated that they were an average of 15 points below white people, this meant that their children would be similarly poorly endowed intellectually. These ideas formed a good part of the basis of scientific racism in the twentieth century and many of those who were the staunchest supporters of the idea had come under Cyril Burt’s influence; including men like Hans Eysenck and Arthur Jensen.  Eysenck was a former student of Cyril Burt’s and Jensen was a student of Eysenck’s. Both men became notorious in the late 1960s and early 1970s for championing the cause of scientific racism.

     In 1969 Arthur Jensen, a psychologist who lectured at the University of California, Berkley, published a piece in the Harvard Educational Review entitled ‘How Much Can We Boost IQ and Scholastic Achievement?’ (Jensen, 1969). His conclusion was that very little could actually be done. He produced evidence for the 15 point gap in measured IQ between black and white pupils and attributed it largely to heredity. This confirmed what many people already suspected, but it marked the beginning of the modern debate on race and intelligence. One of the chief planks in Jensen’s theories was the study of twins who had been raised separately. Two years later Hans Eysenck, whose student Jensen had once been, published two books; one in Britain and the other in the United States. These were Race, Intelligence and Education and The IQ Argument. Eysenck agreed with Arthur Jensen and became embroiled in controversy in Britain of the same kind which Jensen had encountered in California. In a foreshadowing of today’s practices, Eysenck was ‘de-platformed’ by students at the London School of Economics. When he tried to give a speech there on 8 May 1973, the stage was stormed and Eysenck assaulted.

     Cyril Burt had published extensively on what he claimed was definitive proof that the greater part of our intelligence is handed down to us by our parents.  Identical twins are the product of a single egg which has split into two foetuses; known technically a monozygotic or MZ for short. The babies resulting from this process have identical genes. Of course, in the usual way of things such pairs of children are raised in identical environments, which makes it all but impossible to untangle how much of their intelligence is due to nurture and how much to nature. What though if identical twins are separated at, or very close to, birth and raised in different homes? If the homes vary greatly in terms of class, socio-economic background, education of the parents and so on, then this might tell us something very useful about intelligence. If the intelligence of the twins was found to be very similar in later years, this would hint at heredity being the main factor. If, on the other hand, their IQs differed greatly, then environmental conditions would be more likely implicated. The problem is that such instances of MZ twins separated at birth are vanishingly rare. At least, they had always been rare for most researchers other than Cyril Burt (Colman, 1987).

     The twins study about which Burt wrote was hugely impressive for two good reasons and it was hardly surprising that both Arthur Jensen and Hans Eysenck should have relied heavily on his data. He had somehow found no fewer than 53 pairs of identical twins who had, for various reasons, been separated soon after birth and raised separately. This was far more than anybody else had ever written about. Not only that, but Cyril Burt had also apparently managed to investigate the environments in which the children had grown up. By assessing the families in which these twins had been raised, it appeared that almost all the twins had been reared in different circumstances. Burt used a six-point scale to assess the socio-economic status of families, ranging from ‘unskilled’ to ‘higher professional’. By happy chance, he found that the correlation between the home backgrounds of the children he studied was almost zero. In other words, almost all of them grew up in different circumstances, one from the other.

     After measuring the IQs of all the MZ twins he studied, Cyril Burt concluded that the correlation between the pairs was 0.86. No correlation would have been indicated by a score or zero and perfect accord by a score of one. In other words, since the environments were in almost all cases dissimilar, around 86 % of the intelligence displayed must have been from genetic factors alone. This really gave a great boost to those who believed that IQ could not be increased by education. It was seemingly a fixed quantity, handed down at birth and neither home background or schooling made any difference. Little wonder that Jensen and Eysenck were so keen to rely upon Cyril Burt’s findings; his work supported and endorsed their own views on both the probable intellectual ability of the average black person and to what extent this could be improved by spending more on schools.

     Cyril Burt died in 1971 and for the next three years the views of Hans Eysenck and Arthur Jensen on the heritability of intelligence, seemed secure, although they were reviled and detested in some quarters as racists. Then in 1974, some disturbing information came to light. A statistical analysis of the data used by Burt to prove his ideas about intelligence revealed that the figures were simply too good to be true. Since this related to the work on MZ twins, it cast into doubt what had looked to be cast-iron evidence in favour of the largely inherited nature of intelligence. Much worse was to come. In 1976 the British newspaper the Sunday Times published a detailed study Burt’s work relating to identical twins. Much of what he had published on the subject had listed as co-authors and collaborators two women called Margaret Howard and J. Conway. It was they who had seemingly tested the children and arranged the resultant data. The problem was that exhaustive research had failed to find any evidence that these women had ever existed. Before his death, Burt had told somebody that they had both emigrated and he had lost their addresses. Not one person, other than Burt himself, had ever set eyes on Margaret Howard or J. Conway. Burt’s official biographer, Leslie Hearnshaw, was given free access to all Burt’s diaries, correspondence and research notes. Not only was he unable to find any information about Margaret Howard and J. Conway, neither could he find the slightest evidence that Cyril Burt had ever conducted any research himself on identical twins either (Grant, 2007).

     It is hard to overstate what a devastating blow the discovery of Cyril Burt’s fraud was to the world of psychology. No other work on identical twins was anywhere near as extensive as his, nor had others in the field managed to carry out as much research on the home backgrounds in which the children grew up. Both Hans Eysenck and Arthur Jensen were furiously angry, not so much at Burt as at those who had unmasked his deceit. It enabled those who disapproved of their work to ridicule them and claim that the conclusions which they had drawn about matters relating to the intelligence of black people were hopelessly flawed. As we shall see, although some of the data used was unreliable, that did not by any means suggest that Jensen and Eysenck were wholly wrong in the ideas which they were promoting.

     Another factor though was at play when people were discussing and thinking about the heritability of intelligence. It is true that the exposure of Cyril Burt’s mendacity dealt a great blow to those who claimed that the majority of intelligence was inherited, rather than being related to the environment in which a child was raised. Even before this though, there was a vague feeling of unease after the end of the Second World War that somebody should be conducting experiments of any kind on or relating to twins. In the last chapter we considered the devastating effect which the Holocaust had upon discussions in the western world about the two topics of race and eugenics. There too, in the midst of the Holocaust, twins had been the focus of a certain academic.

     Most people have heard of Dr Josef Mengele, the doctor at Auschwitz who carried out the most atrocious medical experiments on prisoners, especially Jews. Like Cyril Burt, Mengele was intrigued by twins and the insight which they might afford to the genetic inheritance of abilities (Rees, 2005). Mengele’s interest in twins caused him to save any he could lay hands on from being sent to the gas chambers of Auschwitz, so that he could conduct research upon them. This was an unprecedented opportunity, for there were quite literally no limits at all on what he could do with his human subjects; up to and including killing two identical twins at the same time with lethal injections and carrying out autopsies on two twins who died at the same hour of the same day; surely a unique circumstance in the annals of such research (Nyiszli, 1973).

     The memory of the ghastly experiments conducted at Auschwitz by Mengele, one of which was injecting dye into children’s eyes in an effort to change their colour, made the very thought of experimenting with and testing pairs of twins a little distasteful to many people. The discovery that Cyril Burt was a pathological liar who had faked his research on twins was enough to make anything touching upon the topic something which most people preferred to keep at arm’s length. It did not help either that both Mengele and Burt were keen eugenicists.

This then is why there has, since the 1970s, been little appetite for research of this kind into inherited intelligence and no funding available for any such studies.

Colman, Andrew M. (1987) Facts, Fallacies and Frauds in Psychology, London: Unwin Hyman.

Grant, John (2007) Corrupted Science, Wisley: Facts, Figures & Fun.

Nyiszli, Miklos (1973) Auschwitz: A Doctor’s Eyewitness Account, London: Mayflower Books.

Rees, Laurence, (2005) Auschwitz: The Nazis and the Final Solution, London: BBC Books.