Genetics + Family Environment Impact Childhood Obesity

A new international study finds that around 35-40 percent of a child’s BMI (Body Mass Index) — how fat or thin they are — is inherited from their parents.

Investigators say that for the most obese children, the proportion rises to 55-60 percent, thus more than half of their tendency towards obesity is determined by genetics and family environment.

University of Sussex researchers used data on the heights and weights of 100,000 children and their parents across the world, including the U.K., U.S., China, Indonesia, Spain, and Mexico.

Investigators found that the intergenerational transmission of BMI is approximately constant at around 0.2 per parent; i.e., each child’s BMI is, on average, 20 percent due to the mother and 20 percent due to the father.

The pattern of results, said 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.

Professor Dolton says, “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.

“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 findings are published in the journal Economics and Human Biology.

Interestingly, the effect of parents’ BMI on their children’s BMI depends on what the BMI of the child is. Researchers discovered that consistently, across all populations studied, the parental effect’ was lowest for the thinnest children and highest for the most obese children.

For the thinnest child their BMI is 10 percent due to their mother and 10 percent due to their father. For the fattest child this transmission is closer to 30 percent due to each parent.

Said Dolton, “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.”

Source: University of Sussex