Leading Article: The genetic tyranny

'LET IT be split, as long as it does not explode,' wrote the Daily Mirror in 1932 when the news broke that Lord Rutherford's Cavendish Laboratory team had split the atom. But explode it did, only 13 years later. The implications of genetic science are as awesome and as perilous for the future of humanity as was the exploration of the atomic nucleus. Can we do a better job - or even as good a job - of handling it?

Advances in knowledge about human genes are usually presented as positive, offering the hope of ridding the world of a lethal disease or a disabling condition, such as cystic fibrosis or Huntington's Chorea. Research is progressing at extraordinary speed - within 15 years, it is estimated, there will be tests to identify the genes related to 1,000 inherited diseases. Scientists have implied that their work is wholly beneficial, designed purely to eliminate 'defective' genes. This is why many gay men have reacted with alarm to last week's news that scientists in America have established a genetic component in homosexuality and are on the track of the gene responsible. The immediate implication is that homosexuality is itself a defect or a disease, as indeed it was classified by bodies such as the World Health Organisation until very recently. A further implication is that parents will be offered tests so that foetuses carrying a gay gene may be aborted as readily as those that carry a cystic fibrosis gene.

This betrays a misunderstanding of the science involved. Cystic fibrosis is the direct result of a defect in a single gene; nobody expects to discover a gene that 'causes' homosexuality in the same way. Sexual behaviour is formed by a combination of genetic and environmental influences - a particular gene is no more to 'blame' than an over-dominant mother. The same applies to, say, diabetes: there is a genetic basis for this condition but you are less likely to become diabetic if you have a Japanese-style, fish-based diet.

It is here that we begin to understand that this is not an issue for homosexuals alone. One in 30 children is born with a genetic problem of some kind - blindness, deafness, mental handicap, for example. Perhaps we can accept the rights of their parents to decide that these are handicaps with which they would rather not cope. But what of a gene that predisposes to cancer or heart disease? Can we tolerate the idea that a parent might abort a child because it has a 50 per cent chance of dying at 45? If not, would we find it more tolerable if the chances were 95 per cent? Two-thirds of the population will suffer and possibly die of an illness or condition that has some genetic component. And that leaves aside all the other things that cause children to disappoint their parents. In the same week as the 'gay genes' made the headlines, reports that other groups of scientists had identified genes for dyslexia passed almost unnoticed. Genes for schizophrenia, alcoholism and manic depression have also been claimed, though not substantiated. No doubt genes for obesity or short sight or susceptibility to sunburn will be found; IQ certainly has some genetic component, regardless of the arguments over the precise proportion. How soon before we are left with what Professor Steve Jones, one of Britain's leading geneticists, has called 'the dictatorship of the normal'? Find awful genetic handicaps, combine them with horrific family circumstances, and you have an unanswerable case for abortion. But you will find you have lost Beethoven.

The question then is where and how to draw the line. Some would argue that scientists should stop meddling with our genes, that their research should cease immediately. This, even if desirable, would be almost impossible to enforce. But critics may well ask why 26 nations are contributing a total of dollars 2bn to an attempt to map the entire human genetic make-up when their governments have not, apparently, given more than a second's thought to possible safeguards against the results being misused. The answer is that these are long-term and complex issues and that politicians, like Sam Goldwyn, are inclined to ask what posterity ever did for them. They should be aware that the age of the 'designer baby' is probably less than two decades away and that, precisely because the problems are so dauntingly complex, some kind of public debate is urgent.