I personally dont see frisk or chara with any gender, though sometimes i imagine frisk being a boy for some reason?? Anyways i really dont care what gender you think frisk or chara are just. please. stop. giving. them. boobs.
despite there gender, they are still children. as toby fox said (IN THE ACTUAL GAME) that all characters with a striped shirt are children, yes, when monster kid said that it was a hint that frisk was indeed a kid, plus sans calls them "kid" and toriel calls them "my child" so, like i dont care if you see frisk as a girl or a boy but like, dont draw boobs on them or make porn of them because yes, it is child pornography even if you age them up, cause there character no matter what you say they are still a child.