system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What makes hypoallergenic dogs/cats hypoallergenic?

I saw someone say that it's because these animals have hair, not fur. What's the difference?
gpt
The part that makes people allergic to cats is actually a protein (FEL D1) found in their saliva. When a cat licks herself, she deposits the protein on her skin, and when it dries off, the flakes become airborne and trigger symptoms of allergy in people. So, it's not the fur that's the issue, it's the dead skin.

In short, there's no cat that's 100% hypoallergenic, they can only produce less of the protein FEL D1 than regular cats. Some cats tend to be preferred because of trial and error, and even then, some of the most likely to not cause allergies still do because maintenance is required (like bathing or brushing) to make those pets optimal.