Lead author Dr. Clare Llewellyn of the University College London Health Behavior Research Center said previous research showed obesity appeared in families, and twin studies suggested this was largely due to genetic factors.
Thirty-two genes were identified as risk factors for obesity.
For this study, researchers used a new method called Genome-wide Complex Trait Analysis to investigate the molecular genetic heritability of body weight in children.
The study was based on data from a population-based cohort of 2,269 children ages 8-11. Researchers looked at whether children who were genetically similar were also similar in body weight.
"These findings are important because they confirmed in children genes play a very important role in determining body weight. At present only a few genetic variants have been discovered, and these explain a very small amount of individual differences in body weight -- around 2 percent," Llewellyn said in a statement. "These findings suggested there were hundreds of other genetic variants influencing body weight were yet to be discovered."
The findings were published in the International Journal of Obesity.