Around 35-40 per cent of a child’s Body Mass Index (BMI) is inherited from their parents, a new study claims.
In research conducted by the University of Sussex, academics analysed data on the heights and weights of 100,000 children and their parents in the UK, US, China, Indonesia, Spain and Mexico.
The researchers discovered that the intergenerational transmission of BMI is approximately constant at around 0.2 per parent, meaning that on average, each child’s BMI is 20 per cent due to the mother and 20 per cent due to the father. For the most obese children, the proportion rises to 55-60 per cent, suggesting that more than half of their likelihood of being obese is determined by genetics and family environment.
Lead author Professor Peter Dolton said the pattern of results is remarkably consistent across all countries, regardless of their stage of economic development, degree of industrialisation, or type of economy.
“Our evidence comes from trawling data from across the world with very diverse patterns of nutrition and obesity – from one of the most obese populations – USA – to two of the least obese countries in the world – China and Indonesia,” he said. “We found that the process of intergenerational transmission is the same across all the different countries.”
Furthermore the study demonstrates how the effect of parents’ BMI on their children’s BMI depends on what the BMI of the child is. Across all the populations looked into, the “parental effect” proved to be lowest for the thinnest children and highest for the most obese children.
For the thinnest child, their BMI is 10 per cent due to their mother and 10 per cent due to their father. For the fattest child, this transmission is closer to 30 per cent due to each parent.
“This shows that the children of obese parents are much more likely to be obese themselves when they grow up – the parental effect is more than double for the most obese children what it is for the thinnest children,” explained Professor Dolton.
“These findings have far-reaching consequences for the health of the world’s children.”
The findings are published in the journal Economics and Human Biology.