Scientists who studied brain- wave patterns in babies a few months old found that fussy babies who fidget and are hard to soothe are likely to become shy and withdrawn children with behavioural problems in later life.
The controversial research into the genetic basis of childhood behaviour was presented at the annual meeting of the American Association for the Advancement of Science in San Francisco. It shows that children with a certain pattern of electrical activity in the brain are significantly more prone to becoming shy and introverted. A parallel study demonstrates that genes play a role in deciding which type of personality a child will have.
Nathan Fox, professor of human development at the University of Maryland at College Park, said babies with a high state of electrical activity on the right frontal lobe of the brain are more likely to be shy and introverted than babies with stronger brain-wave patterns on the left frontal lobe. 'We are now able to predict, based on an infant's behaviour and the physiological activity of his brain, which child is likely to be shy and withdrawn at the age of two,' he said. 'Our studies go up to the age of seven and we feel confident we've identified a physiological pattern that reflects activity on different sides of the brain which are markers or fingerprints for personality.'
The research involved testing 400 children with tapes of recorded speech, moving mobiles and cotton swabs dipped in alcohol to see their reactions. About 20 per cent became unduly aroused and fearful, and this group tended to have electrical excitability in the right side of their brains.
Professor Fox said these children may have trouble making friends and are likely to shy away from being active in a group. They may be more anxious, which can show up as depression or disruptive behaviour in later life, he said. 'What we are saying is that when it comes to personality, we do not start with a blank slate.' Parents can help minimise the risks of problems developing in these children.
Other researchers who studied temperaments in 700 pairs of twins found the first hard evidence that aspects of personality have a genetic component, according to Hill Goldsmith, professor of psychology at the University of Wisconsin at Madison. 'Our genes seem to account for about half the variability we see in temperament.'
He said, however, that upbringing can override a genetic tendency. 'It's a fallacy to believe that anything with a genetic input is not modifiable.'
Jerome Kagan, professor of psychology at Harvard University, in Cambridge, Massachusetts, said the value of researching into the genetics of personality is that a 'sizeable burden of guilt' can be lifted from parents who feel it may be their fault if a child is overly shy and introverted. He said the human brain has at least 150 different chemicals, such as neurotransmitters and natural opiates. 'They determine the firing patterns that make a child a little more active, or a little less active; a little more anxious or a little less anxious.'
Differences between people should come as no surprise because although everyone has these 150 chemicals 'we inherit them in different concentrations - a million different tomato soups', he said. 'That is why there is a large number of different temperaments - some rare, some common - and this is a new area of research. It is just beginning.'