Three kids walk into a classroom — a Christian, a Muslim and an atheist — and they're each given 10 stickers.

Don't worry, this isn't a joke. It's the premise of a research project in which scientists attempted to uncover whether or not a child's religion affected her level of generosity and kindness. In this study, the non-religious kids were decidedly more generous and less judgmental than their religious peers.

The study, which was published in a recent issue of Current Biology, looked at the moral development of kids around the world. It was notable both for its size (1,170 kids) and its scope (the kids were from Canada, China, Jordan, Turkey, South Africa and the United States.)

stickersParticipants included 510 Muslim, 280 Christian and 323 nonreligious children aged 5-12. For the study, the kids met individually with an adult and were allowed to choose 10 of their favorite stickers, the gold standard when it comes to kids' currency. The kids were then told that the adults would not have time to distribute stickers to all of the kids and that, if they wanted to, they could leave some of their stickers in an envelope to be given to kids from their same school and ethnic group. The researchers used these limitations in an effort to remove any biases that kids might feel towards kids from other groups.

On average, the non-religious kids left significantly more stickers behind than either their Christian or Muslim peers. The differences were greater as the kids got older, with religious kids increasingly less likely to share.

For the second part of the study, researchers asked the kids to watch a short video in which one kid did something unkind to another, such as shoving. The kids were then asked to rate how mean they thought the child in the video was and how severely the child should be punished. Once again, non-religious kids seemed to deviate from their religious peers, seeing the incidents as "less mean" and requiring lighter punishments. Muslim kids gave the harshest rankings when it came to rating the severity of the incidents and the necessary punishments.

So the obvious question researchers are asking now is why?

Why would cultures that emphasize morality produce children who are less likely to be kind and generous to their peers? One theory is that religious parents teach children to be good out of respect or fear of a "higher power," whereas nonreligious parents teach children to be good because it's the right thing to do. So religious children may only feel compelled to be kind or generous if they think someone is watching.

Researchers hope to expand on this study by evaluating children in even more countries and by looking at how kids from different religious backgrounds would distribute things within a group.

Inset photo of stickers: Alias Ching/Shutterstock

Religious kids are less generous and more judgmental than their atheist peers, study finds
The effect was greatest as kids got older, with tweens increasingly less likely to share.