system
Given the following post, respond as if you're commenting on Reddit:
human
[The Simpsons] Is there an in-universe explanation for why most of the characters are yellow?
gpt
When Grandpa Abe begins a relationship with Marge’s mother, Homer expresses worry that he and Marge will thus be brother and sister, causing their children to be “horrible freaks with pink skin, no overbite, and five fingers on each hand.”

The implication here is that for those who inhabit the world of the Simpsons, most ethnicities having yellow skin is simply the evolutionary norm. That is how humans developed, and pink skin is a genetic aberration.