'Skinny genes' passed on from parents to childrenGenetically predisposed to be thin
Children are likely to be thin if they have thin parents, new research suggests.
A new study found that children with thinner parents are three times more likely to be thin than children whose parents are overweight, due to 'skinny genes.'
Past research had shown that obesity runs in families, partly because children can inherit a number of adiposity or fatness genes which predispose them to being overweight.
But scientists at University College London say that thinness may also be inherited by children from their parents in the same way, with children of thinner parents being likely to be genetically predisposed to be slim.
In the study, the researchers analysed data from the Health Survey for England. This included the heights and weights of parents and up to two children, aged two and 15 years from 7,000 families, over a five year period.
This information was used to calculate the Body Mass Index (BMI) of both parents and children.
A BMI of 18.5 to 24.9 is regarded as a healthy weight; 25 -29.9 as overweight and 30 or more as obese.
The results found a 'strong association' between children's and parents' body size.
When both parents were in the lower half of the health BMI range, the chance of the child being thin was 16.2 per cent, compared with 7.8 per cent when both parents were in the upper half.
Thinness was defined as having a BMI in childhood which predicted a future BMI of less than 18.5 as an adult.
If both parents were overweight, the chance of having a thin child was just 5.3 per cent, and only 2.5 per cent for children with two obese parents.
Neither the mothers' or fathers' weights, the children's ages or gender or background appeared to have any effect on the child's chances of being thin.
Lead author Dr Katrina Whitaker, from UCL's department of epidemiology and public health, said: "We know from other studies that children's weights are correlated with those of their parents, but previous research has tended to focus on obesity rather than the other end of the spectrum.
Study co-author Professor Jane Wardle added: "Parents are often concerned if their child is thin, but it may just be their 'skinny genes.'
"All genes have two versions, called alleles. We might think of weight-related genes as having a 'skinny' and 'curvy' allele.
"Thinner parents are likely to have more of the skinny alleles, increasing the chance of passing them on to their children. A child who inherits more of the skinny alleles from their parents will be naturally thinner."
This article was published on Tue 4 October 2011
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