"Many times, sociological, behavioral and cultural issues overrides the biological," Bailey said. "One-third of African Americans are still in poverty, and that influences the types of foods you are able to eat."
In another study from the same issue, researchers found that gene variants that have been implicated in a tendency toward obesity played only a small role in a person's BMI.
Previous research in twins has suggested as much as 40 percent to 85 percent of obesity can be blamed on the genes, but the new research shows the influence of genetic variants may be much smaller.
Researchers at the University of Cambridge looked for 12 genetic markers for obesity in more than 20,000 participants from the United Kingdom. Those with at least one gene marker were 3 percent to 14 percent more likely to be obese than those without the marker, while each additional genetic marker raised the risk of obesity by nearly 11 percent.
But taken together, the genetic variations accounted for only about a one percent variation in BMI -- meaning the currently known markers are poor predictors of who is at risk for obesity, according to the study.
Researchers said it's possible that other, more important obesity-related gene variants have yet to be identified.
There's a personal BMI calculator at the U.S. National Heart, Lung and Blood Institute.
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