and sibling correlations in fact suggest a decrease in the heritability coefficient, strengthening the argument for environmental causation of IQ differences. Burt would hardly engage in deliberate fraud in order to bolster a conclusion completely opposite to his own.
What is the moral of this curious story? A talented scientist who works largely alone makes a good many personal enemies. He is sometimes careless and eccentric in his presentation of his studies. He becomes a prominent public figure. Most important, he develops politically incorrect theories on socially sensitive topics. This combination of factors gives his opponents--aided by sympathetic journalists--ample ammunition to attack his reputation.
Such is the essence of the Burt affair. Joynson and Fletcher have disproved some of the accusations and suspicions levelled against Burt, but not all, and not completely. There is room left for doubt. Whether one gives the benefit of the doubt to Burt or to his detractors is still another matter. A convincing defence of Burt is handicapped by his undisputed personal eccentricities and petty foibles, as well as by his failings as an empirical scientist. Since it is next to impossible to prove a negative, no one can confidently proclaim Burt's complete innocence of all charges. He may be guilty of simple carelessness. But the burden of proof rests squarely on those who have proclaimed Burt guilty of fraud. Virtually all of their evidence has proven so flimsy that I believe an impartial jury would rule out the verdict of fraud, not just on the grounds of 'not proven', but simply as not plausible.
A final judgement on Burt would probably not much interest historians of psychology if it had turned out that his conclusions about the heritability of intelligence were wrong. But in the twenty years since Burt died, many scientifically rigorous studies--including a recent MZa-twin replication virtually identical to Burt's--have substantiated the theory that individual differences in intelligence are strongly conditioned by genetic factors. Experts in behavioural genetics now generally agree on this central point. As all the smoke and fumes of the Burt affair dissipate, this should be cause for optimism: the field of behavioural genetics appears increasingly ready-- controversy notwithstanding--to behave as a science like any other.
Beloff H. ( 1980). "A balance sheet on Burt". Bulletin of the British Psychological Society (suppl.), 33.
Burt C. L. ( 1925). The young delinquent. University of London Press.