Up to 40 Percent of Child Obesity Incidences Inherited from Parents

20 Feb 2017 --- Around 35-40 percent of a child's Body Mass Index (BMI) is inherited from their parents, a new study has found, rising to 55-60 per cent for obese children. The study suggests that more than half a child’s tendency towards obesity is determined by genetics and family environment.

The research, published in the journal Economics and Human Biology and led by the University of Sussex, used data on the heights and weights of 100,000 children and their parents spanning six countries worldwide: the UK, USA, China, Indonesia, Spain and Mexico.

The researchers found that the intergenerational transmission of BMI is approximately constant at around 0.2 per parent, meaning that each child's BMI is, on average, 20 per cent due to the mother and 20 per cent due to the father.

The pattern of results, says lead author Professor Peter Dolton of the University of Sussex, is remarkably consistent across all countries, irrespective of their stage of economic development, degree of industrialization, 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,” Professor Dolton says.

“This gives an important and rare insight into how obesity is transmitted across generations in both developed and developing countries.”

“We found that the process of intergenerational transmission is the same across all the different countries.”

The study also shows how the effect of parents' BMI on their children's BMI depends on what the BMI of the child is.

Consistently, across all populations studied, they found the “parental effect” 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.

Professor Dolton says, “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.”

“These findings have far-reaching consequences for the health of the world's children.”

“They should make us rethink the extent to which obesity is the result of family factors, and our genetic inheritance, rather than decisions made by us as individuals.”

Talking with NutritionInsight, Dolton said "This research is the first to examine data from so many countries across the world. The implication is that to some extent individuals cannot control what their BMI is - it is determined for them by the genes they inherit and the other family factors which contribute to obesity. The relative contribution of genetic and environmental factors cannot be separately identified."