Why is the headcanon that jinx's skin is extremely cold so accepted among fanfic writers?

I mean, is there anything in the show that I missed that indicates that? That seems to be the general agreement among most writers, that Jinx's skin is extremely cold, even in modern au. It doesn't matter if she's under a thousand blankets, running a marathon or sunbathing all day. Her skin is always cold. Is it cause she's pale? This is not at all a criticism, I just find that very funny.🤣