I still possess somewhere a paper napkin bearing the seal of the vice-president of the United States, purloined from Air Force Two while writing a profile of Dan Quayle for the Economist. (Mem-entos do not come much more momentous than that.) Filching the napkin was no doubt a minor misdemeanour even then. Today, however, it might be treated more seriously.
There are persistent rumours - unconfirmed, of course - that senior politicians in Britain and the United States are being advised that they should take care not to leave behind any used napkins, or even cutlery and crockery, after a public event. The reason is to prevent some villain from extracting DNA from the traces of politicians' saliva or skin cells on a napkin and using it for a mischievous purpose.
I may be partly responsible for this paranoia. In my book Genome, I repeated a story about napkins told by the leading geneticist Eric Lander of the Massachusetts Institute of Technology. It concerns a gene on human chromosome 19 called the apoE gene. The gene comes in three varieties, and one of those, the E4 version, is associated with a higher-than-average risk of Alzheimer's disease. For those people who have inherited E4 genes from both parents - about 7 per cent of white people - the lifetime risk of Alzheimer's disease is more than 50 per cent.
Here is what Lander said: "Just think what would have happened if some enterprising reporter hooked up with some enterprising scientist in the 1980 presidential election and got cocktail napkins that Ronald Reagan had wiped his mouth with. There is a reasonably good chance that Ronald Reagan is apoE4 homozygous [that is, he has inherited the mutation from both parents], I don't know for sure but the odds are not unreasonable, as there is a family history and all that. Would you have published the story? Would you have invaded his privacy? Would you have said the public has a right to know? Or does he have the right to keep his genome secret? I don't know."
History shows that the world would have been wrong to reject either Ronald Reagan or Harold Wilson for high office on the grounds of the diseases they were to develop in old age. The talents and shortcomings they displayed in office had nothing to do with memory loss. In any case, the technology was not around in 1980. But it is today, and the news that a candidate for high office was at a greater than 50 per cent risk of Alzheimer's disease might yet sink him, whether justified or not. This is not like digging out medical records (the revelation of Senator Thomas Eagleton's electro-shock therapy for depression helped to sink his 1972 attempt to run for the vice-presidency), because it is about the future.
Genetic knowledge is rapidly providing us with the first reliable set of crystal balls. It can already tell the daughter of a parent with Huntington's disease not just if she will also get the disease as an adult, but at precisely what age, give or take about two years. It can tell you, much less precisely, your statistical risk of Alzheimer's disease, and it can give you some hints about heart disease or stroke. This is only the beginning. It is not far-fetched to imagine, within a few years, accurate and cheap DNA tests for your general susceptibility to many mental conditions from depression to intelligence. Should you be worried?
There is one great reassuring answer: life. Very few of the things that matter about a person can be predicted accurately by genes even in principle, and many of the things that can be predicted do not matter. A high risk of heart disease (Dick Cheney), or clumsiness with grammar (both George Bushes), may well be partly genetic conditions. Professor Tony Monaco and colleagues at Oxford recently identified a mutation, in a gene called foxP2 on chromosome 7, that helps to cause "specific language impairment" in some members of a large London family who sometimes have trouble with grammar. If George W Bush turned out to have this mutation, I suspect his popularity would rise rather than fall. Like David Blunkett, he would be seen as having triumphed over a disability.
What is true for politicians is also true for the rest of us. Politicians are employed by the public, so discriminating between politicians on the basis of their genes would be discrimination by an employer. All employment decisions involve some form of discrimination: that is why people are interviewed for jobs. Most rational people can agree that genetic discrimination should join racial and sexual discrimination beyond the pale. Yet the truth is that there are very few things our employers could, even in principle, find out from our genes that would affect their decisions to employ us. IQ? They already ask for exam results. Personality? That's what interviews are for. Gender? No need to consult the chromosomes. Alzheimer's? Usually strikes long after retirement anyway.
Gregory Stock, in his excellent new book Redesigning Humans, asks us to imagine an employer in the future poring over the genes of a candidate employee and rejecting him unseen. O brave new world, you cry, until you learn that the employer was looking for a topless waitress and had rejected the candidate for being (genetically) prone to obesity, bald - and male. Genetic discrimination is all around us already.
In 1999, an American woman named Terri Seargent was diagnosed with a preventable genetic condition called Alpha-1 and sacked by her employer, despite exemplary performance, as soon as she began expensive medical treatment. In taking fright at her medical bills, however, the employer was not so much guilty of genetic discrimination as breaking ordinary employment law. Most expensive illnesses - Aids, cancer and the like - are triggered by environmental, rather than genetic factors. In any case, in Britain, employers only provide health insurance for the top managerial class, not the bulk of the workforce; so it is a middle-class issue with little resonance for social justice. Apart from extremely rare diseases such as Huntington's, there are few chronic illnesses of early or middle life that can be predicted genetically, and are not already partly predictable from life history, pedigree or early symptoms.
It would therefore be foolish to allow fears of genetic discrimination by employers to block efforts to understand and cure disease. Most families carrying Huntington's accept that a risk of genetic discrimination is a small price to pay for progress towards a cure.
In some cases, you can even imagine that responsible employers should help their employees by giving them genetic tests. Just as a very fair-skinned person should probably be discouraged from taking a job as a lifeguard on a sunny beach, so somebody with a genetic propensity to depression might be better off if discouraged from taking a job as a morgue attendant. Far-fetched, I admit, but the world has a habit of throwing up far stranger cases than politicians anticipate.
All of the above is intended to reassure you that genetic discrimination will not become a common habit of employers. But it is emphatically not a call for such discrimination to be legal. Genetic privacy is of paramount importance. Although there may be unexplored loopholes in the current legislation, broadly speaking, no doctor, employer, insurer, policeman or public authority has or should have the right to inspect your sequence without your permission. Earlier this year, Baroness (Helena) Kennedy, who chairs the Human Genetics Commission, called for a new criminal offence of obtaining DNA without consent. In the United States, the judiciary committee of the House of Representatives is now considering a bill sponsored by Representative Lynn Rivers of Michigan to outlaw unauthorised trafficking in personal DNA information.
The implications of genetic prediction for life insurance are certainly immense. However, they are more of a threat to the insurance industry itself than they are to individuals. If two people take a genetic test for Alzheimer's disease and one discovers that he carries two E4 genes but the other has none, the first person may go straight round the corner and buy a long-term care policy from an insurer. The company has thereby taken on a bad risk and missed a good one, and will shortly be in trouble. Little wonder that insurers want to ask us for the results of any genetic tests we take and will one day start to raise premiums if we refuse.
It is admirable that this troubles people so much. They realise that it is quite fair to penalise smokers and dangerous drivers with higher premiums, because smoking and driving dangerously are self-inflicted risks; but they want to pool the risks of the genetic lottery. Whether such idealism will survive its first collision with practice is yet to be seen. Most people would get good news from genetic tests; would they really refuse lower premiums for taking and passing tests? We may find that insurance can work only in a state of ignorance. When every risk is quantifiable, people will have to pay the true cost of their own future. Fortunately, accidents and cosmic rays will ensure that there is always uncertainty.
By far the commonest use of small DNA samples, though, is the forensic one. Ever since Sir Alec Jeffreys first stumbled on the individual bar-codes of repeated sequences called genetic fingerprints in 1984, DNA has been catching criminals. But from the beginning, the technology has also exonerated the innocent. In 1986 Richard Buckland confessed to raping and murdering a girl in the Leicestershire village of Narborough. The police, keen to pin an old case on him, asked Jeffreys to test DNA samples from both victims and from Buckland. The DNA emphatically proved that, though the same person had committed both crimes, it could not have been Buckland. Only months later, when a local man, Colin Pitchfork, refused to take a DNA test, was the murderer caught.
The police, understandably, would like to make us all deposit DNA samples in their databases. They say we have nothing to fear from such an invasion of our genetic privacy. My libertarian instincts rebel at the thought, because I do not believe the police (or any other body) can be trusted to keep my records secure. Here is just one of many far-fetched possible breaches of security. Suppose one day I am on the shortlist for a big job - let's say Archbishop of Canterbury. Suppose a journalist, through his contacts, gets my DNA sample from the police database and discovers a mutation known (by then) to be much commoner among atheists than believers, and splashes it across the tabloids. It might not affect the result but I would feel violated and invaded.
This is not as fanciful as it sounds. Twin studies find unambiguously high heritability in western societies for virtually all personality traits so far tested, including religiosity. In one study, identical twins who had been reared apart were 62 per cent correlated in their answers to a questionnaire about religious fundamentalism; by contrast, non-identical twins - also reared apart - showed just a 2 per cent correlation.
An even more ingenious napkin threat is now being floated. Instead of reading a politician's genome for signs of future disability, why not insert it into an egg and produce a clone of the bloke? Or if cloned Tony Blairs do not appeal, then try celebrities. From a napkin used by Madonna or Britney, you could generate an entirely new version of each without even asking permission of the original, train her as a singer and sit back and rake in the proceeds.
A Californian company (inevitably) has spotted a business opportunity here. For a modest $1,500, the DNA Copyright Institute will analyse and copyright your DNA so as to prevent unauthorised cloning. Gullible celebrities tempted to part with such small change for a modest reassurance should pause to consider if they are not being had. First, DNA cannot be copyrighted because it is not an original work of authorship. Second, reproductive cloning is illegal anyway. Third, given how hard it has proved to sell Nobel prizewinners' sperm and beauty queen ova, it is hard to imagine anybody lending their womb and mothering skills to the far more risky business of raising somebody else's clone. The lesson of reproductive technologies so far is that people use them to overcome their own infertility, not for eugenic purposes. People want their own children, not better children.
Even in financial terms, the cloning project would be absurdly high-risk for the napkin pirate. Fifteen years of heavy investment in a new Madonna would still ride on the sales of the first record. (And imagine if the Svengali had cloned not the singer, but the waitress who had folded the napkin.) Besides, cloning is still unsafe: with the current cloning technology, it appears that any clone would probably be both disabled and liable to age prematurely. Neither would sit well with the teenage music market.
So Blair can probably relax in the knowledge that a napkin thief will be able neither to clone him nor to embarrass him politically. The best test yet devised for a politician's intelligence, judgement and stamina is a route march through the foothills of a political career, not a DNA test. But the unscrupulous can none the less invade the privacy of his innermost essence in a way that could be unpleasant. Perhaps he would be right to remove his used napkins.