The Heritability of Intelligence

There is an important component of human intelligence ("cognitive ability") which is inherited genetically, as has been shown in a previous article (Galton Institute Newsletter March, 1995). This implies, of course, that some part of it must be attributed to environmental factors operating after birth, particularly early upbringing and education. But if there really is a significant genetically inherited component, determined at conception, that has important implications for educational policy and practice.

There is no question that some children seem to be less intelligent and educable than others. But are these differences genetically innate, or do they result solely from environmental factors operating after birth ? If any of the differences are determined at conception (and nobody doubts that some are also acquired in response to environmental effects: but that isn’t the point here), then the educational arguments for selective schools would seem irresistible. If it is the genetically most intelligent children who have the potential to produce the best results from intensive teaching, then they are surely entitled to receive it. And those who are less intelligent will benefit most from a different form of teaching, which will enable them to make the best of what abilities they do possess. That may sound élitist but it does make sense, just as it would be a waste of time to try to train people who are physically no better than average to be champion weight lifters. This is the "hereditarian" view that, through no merit or fault of their own, some people have higher genetically inherited potential than most of the rest, and some lower.

But in these egalitarian times progressive educationists and many teachers are "environmentalists" rather than hereditarians, believing that all are, or at any rate ought to be, born equal. While recognizing that some children seem to be easily taught while others are not, they would attribute this not to genetical inheritance but to bad social conditions and faults in early upbringing. So something should be done about this at school, where those with these "Special Needs" can be given extra attention to bring them up to the same level as all the rest. And that certainly does have beneficial results, even if often less than had been hoped. Similarly, those who are already doing well will benefit from more advanced teaching, to enable them to do even better, and the improvement at the top can be at least as much as at the bottom, and is usually more. But in modern comprehensive schools the really bright often receive less attention than do those who are lagging behind. The result is that the Special Needs of the most intelligent tend to be neglected, so that they are unable to achieve their full potential.

Over the past 30 years or so State education has become avowedly egalitarian. Before that there had been a few highly selective Grammar Schools and many more of the less demanding Secondary Moderns, with some Technical Schools in between. But, with few exceptions, nowadays all State schools are Comprehensive and non-selective, taking the whole of the ability range and with minimal streaming. Independent Schools remain selective however, and they do seem to produce the best examination results.

The Grammar Schools were originally not only academically but also socially selective, with rather few working class pupils. But this was changed in the 1930’s when really bright boys and girls of whatever social class, selected by the 11+ examination, were offered free places in Grammar Schools, and the majority had to be content with Secondary Moderns, of a lower standard academically although better suited to their more modest abilities. That often irrevocably determined their future careers which caused a lot of discontent, especially to those who had only just failed the 11+. And of course mistakes were bound to be made, which were very difficult to rectify later.

After the war a campaign against élitism in education developed, largely led by middle class parents whose offspring, if they failed the 11+, would have to go to the often inferior local Secondary Modern school, unless they could move to the catchment area of a better one, or pay for fully Independent education. And by the early 1970’s almost all State schools, Grammar as well as Secondary Modern, had had to become non-selective Comprehensives, taking the whole ability range. There can be little doubt that this worked to the disadvantage of the most intelligent pupils, who would have done better if taught together by the best teachers in a selective school. And another problem was that "swots", who work hard and do well, are not always admired by the less diligent majority in a comprehensive school, where they may be discouraged or even bullied. As against that, of course, the reasonably intelligent who would have only marginally failed the 11+, especially if they are late developers as they sometimes are, would benefit from the opportunities for promotion in a fully comprehensive school.

It was the late Sir Cyril Burt who had been largely responsible for the 11+ examination, and after the war he became increasingly distanced from most educational psychologists and progressive teachers, who were almost all environmentalists where intelligence was concerned, whereas Burt was certainly a hereditarian. This was the reason for the really rather disgraceful posthumous attacks on Burt, when he was accused of various malpractices including the fraudulent fabrication of data. But it is now clear that, although much of what he published in old age was muddled and badly presented, the charges of fraud cannot be sustained.

The question remains, however, of whether Burt was right in advocating selective education, for the hereditarian reason that intelligence was largely innate. And this has recently been confirmed by the "Minnesota Study" of more than 100 sets of reared-apart monozygotic and dizygotic twins and triplets (Bouchard, T.J. et al., 1990, Science 250 : 223-8), which found that over 70% of whatever it is that is measured by IQ testing is inherited genetically, close to Burt’s original and later much criticised figure.

There are serious questions here, with important implications for educational policy and practice. It may be politically correct to assume that all children are born with the same potential for success, but they obviously do show big differences in intelligence and educability by the time they get to school. If these really are genetically heritable and determined at conception, to treat them as though they were not isn’t likely to give the best results.

C B Goodhart