THE chance of a child becoming obese is strongly linked to its parents' own weight problems, research showed yesterday.

The study showed the link was gender specific - girls whose mothers were clinically obese and boys whose fathers had the same condition were more likely to follow suit at a young age.

But researchers from the EarlyBird Diabetes Study found the trend did not exist between mothers and sons, or fathers and their daughters.

The scientists said the results suggested behavioural rather than genetic factors could hold the key to finding out why so many British children are obese.

The EarlyBird Study, carried out by the Peninsula Medical School in Plymouth, is tracking 300 children over 12 years in the hope of discovering why diabetes - which in the case of Type 2 is associated with obesity - is on the increase in young people.

Data collected by the researchers found 35 per cent of eight- year-old girls whose mothers were classed as obese were also obese, compared with 8 per cent of the daughters of women who were overweight and 5 per cent of girls whose mothers were classed as normal weight.

In the case of boys, 17 per cent of those whose fathers were obese also suffered with the condition, compared with 5 per cent of the sons of men who were just overweight and 3 per cent of those with normal weight fathers. The researchers said the findings showed the daughter of an obese woman was ten times more likely to be obese than a girl with a normal weight mother.

The son of an obese father was six times more likely to be obese than the son of a normal weight man, the study concluded.

But the scientists said children's weight problems bore no relationship to obesity in their opposite-sex parent.

Professor Terry Wilkin, the study's director, said: "Any genetic link between obese parents and their children would be indiscriminate of gender. The clearly defined gender-assortative pattern which our research has uncovered is an exciting one because it points towards behavioural factors at work in childhood obesity.

"These findings could turn our thinking on childhood obesity dramatically on its head.

"Money and resources have focused on children over the past decade in the belief that obese children become obese adults, and that prevention of obesity in children will solve the problem in adulthood.

"EarlyBird's evidence supports the opposite hypothesis - that children are becoming obese due to the influence of their same-sex parents, and we will need to focus on changing the behaviour of the adult if we want to combat obesity in the child."

Type 2 diabetes is linked to unhealthy lifestyles, including a lack of exercise and obesity, and accounts for around nine out of ten cases of the disease.

The other type of diabetes, Type 1, is not linked to obesity and usually develops in childhood or adolescence.

Colin Waine, chairman of the National Obesity Forum, said the study should be "a wake-up call to families to work towards preventing obesity in all members. If the parents heed the advice it will help them as well as their children".