Steve Jones: The Language of the Genes

All these methods interfere with genes. Their acceptability varies from the reasonably uncontentious choice of sperm to a crime where the murder of girl children is concerned. Where to draw the line depends on one's own social, political or religious background; on how acceptable the notion might be that fate should depend on biological merit. All readers of this book would, I imagine, abhor infanticide, and most might tivl that to terminate a pregnancy jusl because it is the wroiij.; m-x w;is also wrong. They might worry less about tin* choice ot X or Y sperm.

The choice of a child's sex can, however, involve more than parental self-indulgence. Sometimes it is a matter of life and death. Many inherited diseases are carried on the X chromosome. In most girls, an abnormal X is masked by a normal copy. Boys do not have this option, as they have but a single X. For this reason, sex-linked abnormalities, as they are known, are much more common in boys than in girls. They can be distressing. Duchenne muscular dystrophy is a wasting disease of the muscles. Symptoms can appear even in three year-olds and affected children have to wear leg braces by the age of seven, are often in a wheelchair by eleven and may die before the age of twenty-five. Parents who have seen one of their sons die of muscular dystrophy are in the agonising position of knowing that any later son has a one in two chance of having inherited it. A couple who have had a son with the illness can scarcely be blamed for a desire to ensure that no later child is affected. They hope to control the quality of their offspring and few will criticise them for doing so. Genetics has changed their ethical balance.

If a couple has a son with muscular dystrophy they know at once that the mother carries the gene. The chance of a second son with the disease is hence far greater than before. It is still just one in two, so that to terminate all male pregnancies means a real possibility of losing a normal boy. Even those who dislike the idea of choice of a child's sex with X-bearing sperm might change their minds in these circumstances. Others would go further and accept the option of an externally fertilised embryo or the termination of all pregnancies which would produce a son.

Now, such choices have become more precise. The gene for muscular dystrophy has been found and changes in the DNA can show whether a foetus bears it. Hundreds of centres use the test. But the method is far from perfect. The gene can go wrong in many ways and not all of them show up. A foetus that appears normal may hence, in a proportion of cases, carry the gene. This complicates the parents' decision as to whether to continue with a pregnancy. To sample foeral tissues also involves a certain hazard. This has become smaller.is technology improves, with a check of foetal cells in the mother's blood, but the risks of the test must themselves be weighed in the moral scales.

As more is found about the genes lhat cause death not at birth, or in the teens, but in middle or old age the dilemmas increase. Given the opportunity, some might avoid the birth of a baby doomed to dementia through Alzheimer's disease in its forties. Others would argue that forty years of life are not to be dismissed; and that, in four decades of science, the cure may be found.

Decisions about the future of an unborn child will, as a result, more and more be influenced by estimates of risk and of quality: by whether the rights of a foetus depend on its genes. Such judgements are not just scientific decisions, but depend on the society and the people who make them. The debacle of the eugenics movement led to an understandable reluctance even to consider the idea of choices about rights based on inherited merit, but the new knowledge means that they are unavoidable.

Galton himself would have been delighted by the idea of preventing the birth of the damaged. The new eugenics can be overt. The Chinese People's Daily is frank in its views. It reported a scheme to ban the marriage of those with mental disease unless they were sterilised with a robust simplification of Mendelism: idiots give birth to idiots!' the eugenical message is often justified on financial grounds. At the Sesquicentennial Exhibition in Philadelphia in 192.6 the American Eugenics Society had a board that counted up the Si00 per second supposed to be spent on people with 'bad heredity'. Sixty yens later, one proponent of the plan to sequence the human genome claimed that the project would pay for itself by 'curing' schizophrenia — by which he meant the termination of pregnancies carrying the as yet hypothetical and undiscovered gene for the disease. The 1930s were a period of financial squeeze for health care. Seventy years on, the state is still anxious to limit the amount spent on medicine in the face of an inexorable rise in costs, with inborn diseases among the most expensive. There is a fresh danger that genetics will be used as an excuse to discriminate against the handicapped in order to save money.

Genetics — science as a whole — owes its success to the fact that it is reductionist: that to understand a problem, it helps to break it down into its component parts. The human genome project marks the extreme application of such a view. The approach works well in biology as far as it goes, but it only goes so far. Its limits are seen in a phrase once notorious in British politics, the late Prime Minister Mrs Thatcher's statement that 'There is no such thing as society, there are only individuals.' The failures of her philosophy are all around us. To say, with Galton and his successors, 'There are no people, there are only genes* is to fall into the same trap.

In spite of the lessons of the past, there has been a resurgence of the dangerous and antique myth that biology can explain everything. Some have again begun to claim that we are controlled by our inheritance. They promote a kind of biological fatalism. Humanity, they say, is driven by its inheritance. The predicament of those who fail comes from their own weakness and has little to do with the rest of us. Such nouvelle Galtonism suggests that human existence is programmed and that, apart from a little selective pregnancy termination, there is no point in any attempt to change it — which is convenient for those who like things the way they are.

After the Second World War, genetics had — it seemed — at last begun to accept its. own limits and to escape its confines as the haunt of the obsessed. Most of those in the field today are cautious about claims that the essence of humanity lies in DNA. Although it can say extraordinary things about ourselves, gcm-iics is one of the few sciences that has reduced its expectations.

In mediaeval Japan, the science of dactylomancy — the interpretation of personality from fingerprints — had it that people with complex patterns were good craftsmen, those with many loops lacked perseverance, while those whose fingers carried an arched pattern were crude characters without mercy. Human genetics has escaped from its dactylomantic origins. The more we learn about inheritance the more it seems that there is to know. The shadow of eugenics has not yet disappeared but is fainter than it was. Now that genetics has matured as a subject it is beginning to reveal an extraordinary portrait of who we arc, what we were, and what we may become. This book is about what that picture contains.

The rich were the first" geneticists. For them, vaj;m* statements of inherited importance were not enough. They needed-and awarded themselves-concrete symbols ol wen It h.ind consequence that could persist when those who invented them were long dead. The Lion of the Hebrew Tribe of Judah was, until a few years ago, the symbol of the Emperor of Ethiopia, while those of England descend from the lions awarded to Geoffroy Plantagenet in i 177. The fetish for ancestry means that royal families are important in genetics (Prince Charles, for example, has 262,142. ancestors recorded on his pedigree). The obsession persists against all attempts to deny it. Heraldry was cut off by the American Revolution, but George Washington himself attempted to make a connection with the Washingtons of Northamptonshire and used, illegally, their five-pointed stars as a book plate.