system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:why are there so many kid with peanut allergies this generation? And why does it seem like only an American problem?
gpt
Your immune system acts like a police force for your body to protect it from foreign particles.

When your body is exposed to bacteria, viruses, or other harmful foreign matter, your internal police force is busy making sure everything is safe.

But what if you don't get much exposure? Your immune system is always active so they start looking for other ways of "working" in order to justify their existence. They start triggering responses from non-harmful things such as pollen or parts of the food we eat.

This is the basis of the "hygiene hypothesis" for the rise in allergies in the recent decades. Because technology allows us to be more and more clean than our previous generations and with fewer children are playing outside, the childrens' immune systems don't experience enough bad things to occupy them. So the immune system decide to target non-harmful or good things to attack.