Research from City and LSE could have significant implications for health policy.

Published (Updated )

Parents' lifestyles rather than their genes are primarily responsible for their children being overweight, according to new research from City University London and LSE.

The research could have significant implications for health policy, with further support for parents to adopt healthy lifestyles urgently required. Wider acknowledgement of the impact of cultural factors in the transmission of obesity is also needed to help combat the increasing prevalence of the condition amongst children.

Comparing the overweight status of biological and adopted children to that of their parents to determine whether children inherit their overweight problems or whether they are the result of the environment they grow up in, the team found that when both adoptive parents are overweight, the likelihood of an adopted child being overweight is up to 21 per cent higher than when the parents are not overweight.

In comparison, children who have two biological parents who are overweight were found to be 27 per cent more likely to be overweight - just six percentage points more than adopted children, showing the relatively small influence of genetics.

Speaking about the research, Mireia Jofre-Bonet, Professor in Economics at City University London, said: "The good news is that our research shows that we can do something about children's weight problems.

"Although initiatives that target schools and children themselves are admirable, our results suggest that the primary focus should be on helping parents adopt healthier lifestyles and be better role models concerning healthy eating and physical exercise."

Using data from Health Survey for England's (HSE) children's surveys from between 1997- 2009 - an annual survey designed to measure health and health-related behaviours - the researchers also noted that the effect of only a mother or father being overweight was more mixed. Among adoptees they found no effect when only mothers were overweight. In contrast, when only fathers were overweight or obese, there was a small effect.

Dr Joan Costa-i-Font, Associate Professor of Political Economy at LSE, said: "This may be explained by the fact that women are still primarily in charge of the cooking in the home and may tend to over feed their children and partners. Any policies designed to influence parents' lifestyles will need to take a holistic approach and focus on both mothers and fathers to be effective."

The research also shows that being extremely overweight, (obese) - in contrast to being overweight - is more strongly influenced by genetics than by lifestyle factors.

The transmission of being overweight or obese from parents to children, due to lifestyle factors, was not found to be affected by children having a full-time working mother.

In their analysis the researchers took into account a number of factors including the parents' education and age and the children's age and gender. They also took into account characteristics that adoptees may have which make them more or less susceptible to being overweight or obese than biological children.

The full paper, entitled 'Vertical Transmission of Overweight: Evidence form English Adoptees' by Professors Joan Costa-Font, Mireia Jofre-Bonet and Julian Le Grand can be viewed here:

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