THE secret of why some children raised in poverty rise above their circumstances to a lifetime’s success, while others suffer lasting problems, may often lie in their genes.

British scientists have discovered that genetic factors can protect children against the damaging effects of social and economic deprivation.

Though growing up in a poor family is well established to be linked to disruptive behaviour and below average IQ, there is huge variation between individual children from similar backgrounds. The research, from a team at the Institute of Psychiatry at King’s College London, indicates that the genetic make-up of these children plays a critical role.

Whether a child from a poor background becomes a rags-to-riches entrepreneur, or ends up drifting between unemployment and prison, appears to depend at least in part on genes.

The findings add weight to the growing scientific consensus that nature and nurture combine to shape human behaviour and health, and are not mutually exclusive forces. They suggest that neither genes nor environment alone are enough to explain how people develop. Rather, genetic factors influence a child’s “resilience”, so that some are better equipped than others to cope with a difficult family or social background.

The research, led by Julia Kim-Cohen, involved 1,116 pairs of twins aged 5, drawn from across Britain, 56 per cent of whom were identical (monozygotic) and 44 per cent of which were fraternal (dizygotic).

Such twin studies provide a powerful means of separating the genetic and environmental influences on behaviour and development. Identical twins share their genes and environment, while fraternal twins share an environment but have different genes.

In the study, the scientists assessed the socioeconomic status of each family, and interviewed the twins, their mothers and their teachers independently about levels of antisocial behaviour.

These data were used to give each family a deprivation score and each child an antisocial behaviour score, and the children’s IQ was tested to provide a measure of intellectual development. Children who scored significantly higher on either IQ or behaviour than the average for their particular socioeconomic group were classed as either cognitively or behaviourally resilient.

The researchers then looked to see whether there were any significant differences between identical and non-identical twins, to determine the extent to which genetics was responsible for the variation. Identical twins were much more likely to share patterns of resilience than fraternal twins, suggesting that genes play an important role in determining this quality. Genetic factors, indeed, were responsible for about 45 per cent of variation in cognitive resilience, and for about 70 per cent of the variation in behavioural resilience.

“There are some genetic reasons why children from similar deprived backgrounds have the differing outcomes they do,” Dr Kim-Cohen said. “There are some children who are always going to be more likely to ‘rise above’ their circumstances.

“We are not saying that two thirds of any individual’s behaviour is genetically determined — rather it is two thirds of the variation in the population that seems to be explained by genes.”

The study, details of which are published today in the journal Child Development, also found that parental actions had an important influence over children’s resilience, independently of genetic factors. In particular, children whose mothers joined them for stimulating activities, such as going for walks or to museums, had higher levels of resilience.

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