system
Given the following post, respond as if you're commenting on Reddit:
human
Why don't people in third world countries have much more acne?

Based on my purely anecdotal experience and minimal traveling to third world countries, one thing that occurred to me was that, especially with all the marketing in the US you would think that if teens didn't wash their  faces they'd get crazy acne. But that doesn't seem to be the case. Is all acne cream and whatnot a sham? Do I just have skewed perspective?
gpt
While some acne products can reduce your acne, and good hygiene tends to be important in doing so, acne isn't *caused* by not washing your face. It ultimately comes down to genetics and hormones. It's reasonable that some populations might be less genetically predisposed to acne. Certain foods that are very common in Western diets (sugar, dairy) also have some studies suggesting they have an effect on hormones or on acne in general.