Today, John Sulston has realised his life`s dream. Unravelling the sequence of the human genome has been compared to landing on the moon, inventing the wheel or discovering the Holy Grail. Yet the Nobel Prize winner before me is a little more modest “Well, I suppose it was a big job,” he blushes, “and it very nearly went private. But today`s announcement proves that we did it.” He grins. “Isn`t that great!”

A humble, laboratory scientist who “doesn`t like crowds,” I meet Sir John in the deserted cafeteria of Edinburgh`s Royal Museum. It’s the opening week of the Edinburgh International Science Festival and Sulston is here to give a talk entitled ‘What should our genes be used for?’ An hour seems a little on the short side. The war may have stolen today’s front page, but like Iraq, the genome project has divided public opinion and split the scientific community into hawks and doves.“We fought to keep the whole thing public,” Sulston declares, “but now we’re going to have to fight against the patenting of many important genes. And this time it’s going to be far more difficult, because we’re not just fighting an individual, we’re really fighting our whole profit-driven society.”

In the quest to decipher the book of human life, Sulston was the UK head of the publicly funded Human Genome Project, battling to make the sequence data freely available to the whole research community. His opponent, the millionaire businessman Craig Venter, head of Celera genomics, was aiming to monopolise the genome for private profit. While Venter flew by Lear Jet and held interviews in his powerboat, Sulston, a sandal-wearing, self-professed child of the sixties, drove to work in his second-hand car.

The press loved it. They wrote of a battle of good versus evil, a titanic struggle rarely seen in science and having more in common with science fiction novels. “Does that make you Gandalf or Dumbledore?” I ask Sulston. “That depends who you are,” he chuckles. “The Economist and the Financial Times think I`m a nutter. I’d like to think of myself as a practical socialist, but there are some things which you can not own for profit. The Human Genome is one of those.”

Today`s announcement heralds the completion of the 99.999% accurate ‘gold standard’ genome. The timing coincided nicely with the 50th anniversary of Watson and Crick’s discovery of the DNA double helix. Fifty years from now, we may be celebrating cures for cancer and enjoying medical prescriptions tailored to our personal genetic make-up. But will they be available to all, or only the wealthy? It all depends on a few landmark court cases, relating to the bio-capitalism Sulston has compared to “the Klondike goldrush.”

“Biology is offering scientists the prospect of generating wealth, but only if we play the game, file our patents and are greedy” explains Sulston. “Just look at Myriad (a US biotech giant). They`ve taken out a broad patent on a gene involved in breast cancer, which stops any scientist in the US from doing anything with it. Now they`re charging $2500 per breast cancer test, when it doesn`t cost anything like that. It`s simply not productive, this idea that you can own a gene sequence. Genes are discoveries, not inventions.”

While Sulston`s bio-skepticism is firmly focused in the present, the rest of us are more concerned with nightmare visions of a genetically engineered future. When it comes to Brave New Worlds, we’re spoilt for choice. Take for example the film Gattaca, in which newborn babies immediately undergo blood DNA tests. Within seconds, a computer read-out reveals the children’s likely cause of death: heart disease, colon cancer, stroke... sounds far-fetched? Think again. Genes associated with these very conditions are already well studied. The prospect of genetic fortune telling is not far off.“There’s a risk of discrimination if our genetic details are not kept private” warns Sulston. “We must extend our current laws to prevent our employment being predicated by our genes. But then of course, you could argue for exceptions in certain very dangerous jobs. For an airline pilot you would perhaps want screen out people who would be at high risk of suffering from fits or attacks. But in general, as with race and gender, we must not be separated by our genetic differences.”

Admirable sentiment, but in practice it it will be very hard deciding where to draw the line. Already, studies have identified genetic abnormalities which pre-dispose to violent behaviour, a finding which raises all sorts of ethical dilemmas. Would the police have a duty to monitor such individuals? Could a murderer escape charges on the basis of their genes? “At the moment, we don`t know nearly enough to take those kind of decisions” warns Sulston. “Let`s be clear, people are more than just the sum of their genes, the environment plays a massive role. Most of the really interesting things: behaviour; personality; our minds; they won`t compute precisely from our genes. In fact, there are very few traits which will.”

One of the exceptions is our facial structure. A few years from now, it should be possible to create an accurate photo-fit from a single human hair. “That may be valuable for police forensic work,” admits Sulston. “But I don`t find that especially sinister. Unless of course, you have a bent copper. But therein lies an important point: it`s not the knowledge itself which is dangerous, it`s our application of it.”

In fact, there is another, more controversial application of the genetic photo-fit: ‘designer’ babies. In the wake of the Hashmi court ruling, we already have the scientific capability to select an IVF embryo on the basis of its genetic make-up. In the future, couples with enough money may wish to create a series of embryos, study their genes and choose a child with the most desirable appearance. They may even be able to buy their children extra chromosomes, carrying ‘luxury’ genes for superior intellect, health and even happiness. These would in turn be passed on to their grand children, placing them atop a nascent genetic hierarchy. Sulston finds this all rather far-fetched.”I think the super-race girls would just shag the normal boys and their genes would get all mixed up again. I mean, they`d really have to lock up their modified daughters, wouldn’t they? Or perhaps they could engineer a molecular chastity belt.”

For Sulston, these genetic nightmare scenarios are about as plausible as Prince Charles’ scare story over nanotechnology and the grey goo. Dramatic advances in science will always attract fascination and horror in equal measure. For this very reason, the main attraction at this year`s Science Festival is not Sulston, nor Richard Dawkins, nor any other scientist for that matter. In the museum hall next door, Dolly the Sheep stands proudly on display. Surrounded by star-struck kids, she has easily usurped Sulston as the cuddly face of science. Yet on closer inspection, the notice below reveals that she died unexpectedly young. It is not clear whether this had anything to do with the cloning procedure.

In fifty years, might we look back on Dolly’s death as an unheeded warning? “No,” he smiles; “I think Dolly is a wonderful achievement. She proved that we can engineer farm animals to produce essential medicines in their milk. If she`s a warning, it`s that we should never, ever attempt to clone humans. It took over 200 attempts to clone Dolly: The others either died or were terribly deformed. That`s why I find it unbelievably cynical, this scam that the Raelian sect [who claim to have cloned a human] carried off. They`re just impresarios trying to hoodwink us into giving them money. And yet, the journalists go along with them! Even though it`s unethical, immoral and probably impossible, the journalists report it. Now I find that really sickening.”

So what next for Sir John? “I think I, along with the other genome experts, now have a responsibility to educate the public. We must help them to take ethical decisions collectively.” Quite how we will do this is anyone’s guess, although the government’s forthcoming ‘public debate’ on GM Foods may give an indication. I put it to Sulston that the public feel they have even less say over ethics in science than they do over the war in Iraq. He sighs. “Yes, I suppose you`re right. But we have to get it for them. I`m not sure how yet, but I intend to do something about it.”

I can`t help feeling that to win this battle, even the gallant Sir John might need to buy himself a few extra genes. But having succeeded in his quest for the book of life, the child of the 60s tells me he is even more determined to make the world a better place. “Recently, I’ve become involved with the Humanists and they have a wonderful saying: ‘We believe in life before death.”