Fat Kids, Skinny Kids

| Mon Nov. 28, 2011 12:13 PM EST

If you take populations as a whole, you find that they become fatter as they become more developed. That's because they have more money, their lifestyles are more sedentary, and they eat more processed food that's high in fat and sugar.

But what about individuals? What explains why some kids are overweight and others aren't? Sarah Kliff gives us a tutorial:

Studies have found that, of the many home-environment factors at play, maternal obesity is the best predictor of childhood obesity, even more so than low family income or less cognitive stimulation.

But more recent research, particularly a highly cited study in the American Journal of Clinical Nutrition, suggested that was more a question of genes than habits. The study, which followed 5,092 pairs of British twins ages 8 to 11, found that the most influence parents have on obesity is actually genetic, a factor of inheritance, rather than the environment. “Contrary to widespread assumptions about the influence of the family environment, living in the same home in childhood appears to confer little similarity in adult BMI [body mass index],” authors Jane Wardle, Susan Carnell, Claire Haworth and Robert Plomin write.

....“Although contemporary environments have made today’s children fatter than were children 20 years ago, the primary explanation for variations within the population, then and now, is genetic differences between individual children,” they write.

This hardly absolves parents from trying to instill good eating practices in their kids or the food industry from assaulting the airwaves with fat-laden crap. But it does suggest that maybe we should ease up on all the brickbats aimed at bad parenting. In many cases, the modern food industry is knocking on an open door.

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