A new study has found that those with a younger sibling are at a lower risk of becoming obese, a new lead that could result in medical breakthroughs.

The study found that those without a sibling had triple the rate of obesity by the time they reached the first grade, according to a statement from the University of Michigan Health System. The study involved 697 kids and was published in the journal Pediatrics.

Scientists aren’t sure the reason behind this, but it is a promising new lead in better understanding why children become obese, and therefore could lead to new ways to stop obesity in its tracks from an early age.

There are some theories that are being proposed, including that those with siblings are more likely to spend more time playing instead of sitting in front of the television, and it’s also possible the parents are more health conscious with younger children in a way that could “trickle up” to the older children.

“Research suggests that having younger siblings – compared with having older or no siblings – is associated with a lower risk of being overweight. However, we have very little information about how the birth of a sibling may shape obesity risk during childhood,” senior author Julie Lumeng, M.D., a developmental and behavioral pediatrician at U-M’s C.S. Mott Children’s Hospital, said in the statement. “This study is believed to be the first to track subsequent increases in BMI after a child becomes a big brother or sister.”

More research will be needed, however, she added.

“We need to further study how having a sibling may impact even subtle changes such as mealtime behaviors and physical activity,”Lumeng said. “Childhood obesity rates continue to be a great cause of concern. If the birth of a sibling changes behaviors within a family in ways that protect against obesity, these may be patterns other families can try to create in their own homes. Better understanding the potential connection between a sibling and weight may help health providers and families create new strategies for helping children grow up healthy.”