According to a new study, overweight and obese kids inherit about 35 to 40 percent of their parents' BMI.

BMI Scale
Credit: Olivier Le Moal/Shutterstock

If you're worried about your child's weight, you should probably look in the mirror. Because according to a new study out of the University of Sussex, kids are about 35 to 40 percent likely to inherit their parents' BMI. Whoa!

The researchers used data on the heights and weights of 100,000 children and their parents in six countries—the UK, USA, China, Indonesia, Spain, and Mexico. They found that the most obese children were 55 to 60 percent likely to inherit their BMI from Mom and Dad (with 30 percent coming from each parent), while the thinnest children saw a much lower parental effect—with only 10 percent of their BMI attributed to their mother and 10 percent to their father.

"This shows that the children of obese parents are much more likely to be obese themselves when they grow up," explained lead author Peter Dolton, professor at the University of Sussex in Britain. "The parental effect is more than double for the most obese children as compared to what it is for the thinnest."

And here's something else: Dolton said the pattern of results was consistent across all countries, regardless of economic development, degree of industrialization, or type of economy. "Our evidence comes from trawling data from across the world with very diverse patterns of nutrition and obesity—from one of the most obese populations (USA) to two of the least obese countries in the world (China and Indonesia)," he explained. "We found that the process of intergenerational transmission is the same across all the different countries."

Pretty surprising. Which is why Dolton said these findings have far-reaching consequences for the future health of our children. "They should make us rethink the extent to which obesity is the result of family factors and our genetic inheritance," he explained. "Rather than decisions made by us as individuals."

Hollee Actman Becker is a freelance writer, blogger, and mom of two who writes about parenting and pop culture. Check out her website for more, and then follow her on Instagram and Twitter