Does "chemical thing" refer to "something obvious"? I don't understand what "chemical thing" means.
Native speaker’s answer
Rebecca
The root of the word "chemical" stems from "chemistry." In terms of relations between people, "chemistry" refers to the emotional or psychological interaction between people. In this case, Joey is explaining that his negative reaction to Janice is something natural and psychological, i.e. a thing he cannot change. Ex: The chemistry between the main couple in this movie is great. I suggest you watch it! Ex: I can't control my feelings towards Rachel. It's a chemical thing.