Science and Technology: Is there a gene for genius?: One is about to be tracked down, though thousands are probably involved. But early mental stimulation is equally essential to human intelligence. John McCrone reports

DR HOWARD GARDNER of Harvard University believes that geniuses are largely made. He has banned television from his home because he fears it might rot the minds of his family. He makes time every day to listen to his seven-year-old son, Benjamin, play the piano - even if it is no more than a few minutes during a transatlantic phone call while he is away at a conference.

Dr Sandra Scarr of Virginia University, president of the Society for Research in Child Development, believes geniuses are largely born. She says parents should not worry too much about whether to take their kids to a ball game or to a museum. Talent will out.

It seems psychologists are as divided as ever over the issue of nature versus nurture. This may, however, be about to change. A conference organised earlier this year by the Ciba Foundation brought to London some of the biggest names from both sides of the debate. Startling results from unpublished work were revealed - and the beginning of a consensus could be discerned.

The most exciting results came from those working on the biology of individual differences. Dr Robert Plomin of Penn State University, working with a team from Cardiff University, hopes to announce within the next few months that he has tracked down one of the genes that plays a part in determining intelligence. An unnamed gene has been identified but the results have yet to be confirmed.

At present, it is believed that genes account for at least half of what researchers call 'g' - the general cognitive ability that IQ tests are supposed to measure - while environmental influences account for the other half. But so far the evidence for a genetic component has been purely statistical, being inferred from comparisons of twins and other such hereditary studies. Plomin's method makes use of new gene mapping techniques and promises to provide direct evidence of the role that genes play.

Plomin stresses that the discovery of a first gene does not mean the riddle of intelligence has been solved. A single gene will code for only one of the many neurotransmitters and cell proteins that are the building blocks of the brain. This means that hundreds, if not thousands of genes must be involved in intelligence. The identification of even one gene does, however, have immense implications for the nature/nurture debate.

Another innovation, the computerised brain scanner, has led to a second discovery by those seeking the biological component of mental abilities. Professor Camilla Benbow of Iowa State University is head of a long-term study of the mathematically gifted. For many years she has been puzzled as to why so many of the children in her study should be boys - at the top level, boys outnumber girls by 13 to one. In a soon-to-be-published paper, Benbow reveals that the gifted boys' brains appear to process spatial information in a very different way from those of average boys and even of gifted girls.

The children in the study were scanned while being presented with a simple visual

puzzle. The boys of average ability and the gifted girls showed strong activity on both sides

of their brains as they thought about the puzzle. However, the gifted boys responded very differently. There was a sudden drop in act-ivity in their left hemispheres - the side of the brain most involved in language - and an exaggerated reaction on the right, the side strongest at spatial thinking. It seems that the brains of boys with mathematical talent operate in a way that is physically distinctive.

Benbow says she was surprised that the gifted girls should lack this pattern of response. The only explanation she has is that male brains have a tendency to become more lateralised during development; when this lateralisation is taken to an extreme, unusual spatial abilities result.

Because females do not have this tendency (lateralisation is known to be hormonally governed), girls who perform well in mathematics are doing so because of a more general mental superiority. And because statistically such all- round ability is less common, this would be the reason for there being fewer mathematically gifted girls.

Benbow is quick to add, however, that cultural expectations probably exaggerate the imbalance. In China, where girls are more likely to get encouragement in mathematics, the number of gifted boys exceeds that of gifted girls by four to one rather than the 13 to one seen in the United States.

Both Plomin's and Benbow's findings would seem to give ammunition to the argument that exceptional mental abilities are largely innate. But the Ciba conference heard equally strong evidence for the role that environmental factors play in creating genius. A theme repeatedly heard from the speakers was that special children invariably have special parents.

It is a popular myth that great prodigies - the Einsteins, Picassos and Mozarts of this world - spring up out of nowhere as if touched by a divine finger. The archetype is Carl Friedrich Gauss, born into a supposedly illiterate family of labourers, who grew up to become the father of modern mathematics.

Professor William Fowler of the Massachusetts Centre for Early Learning has attacked this myth, saying that when he looked into Gauss's childhood, he found that Gauss's mother had been teaching him numerals at the age of two. His father had been a foreman, not a labourer, and played calculation games with him. Furthermore, Gauss had an educated uncle who taught him sophisticated maths at an early age.

It is the same story with other prodigies. Einstein's father was an electrical engineer who fascinated his son with practical demonstrations of physics. Picasso's father was an art teacher who had young Pablo copying still lifes at the age of eight. Mozart's father was a court composer who was teaching his son to sing and play almost before he could walk. 'In every case, when you look into the backgrounds of great people, there is this pattern of very early stimulation by a parent or mentor figure,' Fowler says.

But what sort of parental stimulation should it be? The conference heard plenty of evidence that, too often, parental pressure and attempts at 'hot-housing' children result in burn-out rather than giftedness. Professor Mihaly Csikszentmihalyi of the University of Chicago reported on a study which identified two kinds of parental style - the supportive and the stimulating.

Supportive parents were those who would go out of their way to help their children follow their pet interests and praised whatever level of achievement resulted. Generally, such parents created a harmonious home governed by clear rules. Stimulating parents were more actively involved in what their children did, steering them towards certain fields and pushing them to work hard, often acting as a tutor.

Csikszentmihalyi's study followed four groups of children: one with supportive parents, one with stimulating parents, one whose parents combined both qualities and a final group who offered neither. The children were given electronic pagers; when these buzzed at random intervals during the day, they had to make a note of what they were doing and assess how happy and alert they felt.

The not too surprising result was that the children whose parents were simply supportive were happier than average but were not particularly intense in their concentration when studying or working on an interest. The children who fared best were those whose parents were both supportive and stimulating. These children showed a reasonable level of happiness and a very high level of alertness during periods of study.

Children whose parents were stimulating without being supportive were candidates for burn-out. These children did work long hours, but their alertness and happiness during study time was far below that of children in more balanced family environments.

Another crucial factor stressed at the Ciba conference is the need for parents to have proper conversations with their children. Through having the chance to talk with adults, children pick up not only language skills but also adult habits and styles of thought. One reason why prodigies such as Picasso and Einstein had a head start in life was that they had parents who demonstrated how to think about subjects like art or physics at a very early age.

Professor Fowler said a survey in Holland showed that a typical father spent just 11 seconds a day in conversation with his children. A more recent study in America produced a somewhat better result, but the fathers in question were still talking to their children for less than a minute a day.

It is not just the time spent that counts, Fowler says, but also the way in which a parent talks. A parent who brushes off a child's questions or gives dull answers will be imparting a negative, narrow-minded style of thinking. On the other hand, parents happy to take a child step by step through an argument, encouraging it to explore ideas, will foster an open and creative thinking style.

Fowler is attempting to show this experimentally with a study in which groups of parents are taught how to have constructive conversations with their toddlers. Fowler says these children have shot ahead of their peer group in language ability, intellectual ability and even social leadership skills. While the study is not yet complete, the children appear to have been given a lasting advantage.

So what is the outlook for parents who do everything right, those who manage to be both supportive and stimulating, who are good at demonstrating thinking skills to their children and successful at fostering a self- motivated approach to learning? Would such parents be guaranteed to have a gifted child?

There was general agreement at the conference that there is no denying that genuine biological differences exist between individuals; geniuses need to be lucky in both their genetic make-up and their parents. The most significant implication would seem to be that while most people are in a position to fulfil their biological potential - that is, barring serious illnesses or dietary deficiencies, they can be certain their genetic capacities will be fully developed - there can be no such certainty that they will grow up in the environment necessary for that development.

So although knowing more about the biology of genius is all very interesting, it is research into better parenting and educational techniques that will have lasting significance.

John McCrone's latest book, 'The Myth of Irrationality: The Science of the Mind From Plato to Star Trek', was published by Macmillan last week ( pounds 16.99).