Obesity in the Family: How Siblings Weigh In

Sibling obesity had greater influence than parent on child risk of obesity

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) A family with at least one obese adult may be more likely to have an obese child. But a bigger influence may be other children in the home.

A recent study found that a child was much more likely to be obese if their sibling was obese than if only one of their parents was obese.

In fact, the influence of a sibling's weight appeared to be more than twice as much as that of the parents' weight.

Siblings' influence on one another was even stronger if they were both the same gender.

"Teach your children healthy eating habits."

This study, led by Mark Pachucki, PhD, of Harvard Medical School, looked at whether children's risk of obesity was related to the weight of their parents or siblings.

The researchers analyzed data from a survey of 10,244 households in 2011.

One or two children were present in 1,948 of these households, and the adult responder provided information on the family's income and race/ethnicity.

The adult responder also provided the adults' and children's height and weight, the amount of physical activity they all got and what food was typically kept in the house or was available in the neighborhood.

Using this information, the researchers calculated associations between the weight of the children and the adults in the homes.

The findings revealed that children were at a higher risk for obesity if others in the family were also obese.

In homes with only children, the children were 2.2 times more likely to be obese if one of their parents was obese.

Adding an obese sibling to the mix, however, had a bigger impact on a child's risk of being obese than the parents' weight.

If the younger sibling was obese, the older child was more than five times more likely to be obese, even though older children were only 2.3 times as likely to be obese if their parents were but their sibling was not.

Similarly, an older obese sibling put the younger sibling at 5.6 times greater risk of being obese.

Yet, if an older sibling was not obese, the younger sibling was not at any higher risk of obesity even if one of their parents was obese.

The researchers discovered these associations were even stronger if the siblings were both boys or both girls.

In line with other studies, the researchers also found that children who were obese were also less likely to be regularly physically active.

The researchers concluded that focusing on the influence of siblings might be one way to combat obesity.

This study was published July 8 in the American Journal of Preventive Medicine.

The research was funded by the Robert Wood Johnson Foundation Healthy Eating Research program and Health and Society Scholars Program. The authors reported no conflicts of interest.

Review Date: 
July 8, 2014
Last Updated:
July 8, 2014