Just occasionally you stumble across an idea so radical that you have to catch your breath at its sheer outrageousness. If it is about science and you are not a scientist, the best thing to do at this point is to retreat into a darkened room, wrap a wet towel around your head and see if you have understood it.

Which is what I've done (metaphorically speaking) and the idea shows no sign of retreating. It is this: the latest medical research, some of it so new that it has not yet been published, suggests that the human genes that govern our character - physical make-up, health, prospects for survival and so on - may not be as all-powerful as we have been told.

They may be altered by the environment, not just over hundreds and thousands of years, but in the space of a couple of generations; that, far from being “unconscious, blind replicators”, as Richard Dawkins puts it, they may be adversely affected by their surroundings; and those acquired characteristics can be passed on to our children; finally, the behaviour of a gene can possibly be modified in the course of the first few years of a human being's life to head off the onset of an otherwise preordained disease.

At the risk of being hauled before the modern equivalent of a papal inquiry and forced to recant, I call in evidence the distinguished Oxford- based neurologist, Professor George Ebers, who has been studying that most baffling disease, multiple sclerosis (MS), in his native Canada. I listened to him last week, and sat up straight when he used the phrase “modified DNA” as a possible explanation for the astonishing disparity between men and women who suffer from MS.

Modified? I thought the whole point about DNA was that it was immutable, the genes handed down from generation to generation, stern, inflexible - and selfish. Or, as Professor Dawkins puts it: “They are in you and me; they created us, body and mind; and their preservation is the ultimate rational for our existence. They have come a long way, those replicators. Now they go by the name of genes, and we are their survival machines.”

The new evidence seems to suggest something different. Over the past 60 years in Canada, Australia and parts of Scotland, rates of MS have been increasing, with the gap between male and female sufferers steadily widening. Women are suffering more, to the point where, in some places, the ratio is more than three to one, and babies born in early spring or winter fare substantially worse.

Furthermore, when individual familes with a history of MS are studied, it is found that this female susceptibility differentiates even between identical twins, and can be found in cousins and other relatives, passed on in the female gene.

So this is a disease that is gender-specific and getting worse among women. Because the weight of medical evidence has always pointed to genetic suceptibility as the underlying cause of MS, this is deeply puzzling. Why should one twin suffer and not another, when their DNA is identical? And why should women suffer more?

The more researchers have examined the evidence, the more they have begun to believe that the explanation must lie in the environment - in some element or combination of elements in diet, climate, lack of vitamins, pollution or other external factor that is affecting the susceptible female gene.

Here it is worth introducing a word with which we may all grow familiar over the next two or three years - “epigenetic,” which is used to describe the inheritance of changes caused by environmental factors.

The articles that have begun to appear in medical journals are increasingly confident in the language that they use. They report that “the environment is constantly altering gene expression through the modification of [its] profile”. They say that “an ‘epigenetic' mark may be added to or removed from gametic DNA [containing sexual reproductive cells] in mothers”. They add that “these changes may remain through cell divisions for the remainder of a cell's life, and sometimes these changes can last for multiple generations”.

But here is the upside. If Professor Ebers and his fellow researchers are right, then a gene susceptible to MS may be altered to avoid it. In other words, a dodgy gene, caught early, can be taught to resist rather than adopt the disease for which it is heading. Is Professor Ebers right? I am in no position to judge. But I like the forthright way in which he approaches what was once regarded as the hallowed teritory of the gene supremacists. And, at the very least, he is suggesting a rethink of the balance between the nature and nurture argument.

It is always good to introduce a bit of heresy into a scientific argument, and I look forward to the fierce debate that lies ahead. It was, after all, Professor Dawkins himself, high priest of gene theology, who wrote: “If a scientist hears, or reads about, a good idea, he passes it on to his colleagues and students. He mentions it in his articles and his lectures. If the idea catches on, it can be said to propagate itself, spreading from brain to brain.” So, here goes.

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