Having obese brothers and sisters is a more revealing indicator of child obesity than having obese parents, according to new study published in the American Journal of Preventive Medicine.

After surveying adults in 10,244 American households, research found that the likelihood of childhood obesity varies with the number of children in a household, as well as their gender, according to the study. In a single child household, a child is 2.2 times more likely to be obese if a parent is also obese and in families with two children, the data showed a stronger relationship with sibling obesity than with parental obesity.

“The family environment is known to exert a strong influence on the trajectory of children’s health, and prior research has done a great deal to illuminate connections between parent and offspring obesity,” said Mark C. Pachucki, PhD, Mongan Institute for Health Policy at Boston Massachusetts General Hospital and lead investigator of the study.

Dr. Pachucki said others have also found that obesity is also often correlated between siblings.

“Our study extends these findings by integrating data on both parent-child, and sibling relationships. We found that obesity status of a younger child’s older sibling is more strongly associated with a child’s obesity than is the parent’s obesity status,” said Dr. Pachucki.

For more information, visit www.ajpmonline.org.