She’s a character you’ll find replicated across popular culture: The grandmother whose house always smells like chocolate chip cookies and who lets the kids eat ice cream for dinner.

She’s a cliché, for sure, but science shows there is some truth to the idea that grandparents are prone to indulging kids in unhealthy ways. Fortunately, talking about it can help reduce the health risks without reducing time with Grandma and Grandpa.

Recently published research out of the University of Glasgow, suggests grandparents are inclined to let kids overindulge in junk food when they’re over, and aren’t keen to let the kids play outside because they fear they’ll lose them. This, combined with the fact that some grandparents are actually still smoking around the children (even when they had been asked not to) raise some red flags for researchers examining the impact grandparents’ habits have on kids’ long-term cancer risk factors.

“Given that many parents now rely on grandparents for care, the mixed messages about health that children might be getting is perhaps an important discussion that needs to be had,” says the paper’s lead author, Dr Stephanie Chambers.

Chambers and her colleagues examined 56 previous studies with data from 18 countries. All the studies looked at child care provided by grandparents who are not the primary caregiver to their grandchildren. They found that grandparents often disregard mom and dad’s wishes when it comes to nutrition, and role-model negative behaviors.

“Exposure to smoking and regularly treating children increases cancer risks as children grow into adulthood,” says Chambers. “It is also clear from the evidence that these risks are unintentional.”

The researchers suggest grandparents could benefit from targeted public health messaging about kids’ health issues and from some hard conversations with their own kids. “From the studies we looked at, it appears that parents often find it difficult to discuss the issues of passive smoking and over-treating grandchildren,” Chambers explains.

According to Angela Bowen, author of Today’s Grandmother: Your Guide to the First Two Years, parents need to be very direct when discussing things like a child’s diet and exercise with caregiving grandparents. “You have to say, ‘This is our child and this is how we are doing things,’” Bowen says in a previous interview with Motherly.

Expert tips for grandparents

Don’t use food to control behavior

Research indicates a lot of grandparents turn to treats when kids are having a tantrum, or in order to reward or bribe them. Experts suggest more productive ways of stopping tantrums, and encourage caregivers to use non-food rewards (if parents are using rewards at all). A trip to the park or a special book might be a better “treat” for kids in the long run.

Don’t buy juice

When we were growing up, there was always juice in the fridge (and in our sippy cups) but these days, the American Academy of Pediatrics cautions against fruit juice. It recommends no juice at all for babies, and really limited consumption for older kids. If juice isn’t an option at a child’s home, grandparents shouldn’t serve it at their house, either.

Take them outside

The physical activity levels of grandchildren are linked to how physically active the grandparents are themselves, so modeling healthy habits makes a huge difference. Going outside is good for you both (and might help the kids chill out a bit during indoor time) so don’t let a fear of losing them stop you from going for a walk or to the park.

According to the researchers, if grandparents help encourage healthy habits early in life, kids have an easier time keeping up a healthy routine as an adult.

No one is suggesting grandparents don’t bake cookies with their grandkids, but the science does suggest they may want to seek out some reduced sugar recipes. ?