Board Thread:General Discussion/@comment-24100805-20160201152915/@comment-36541110-20181202211945

I'm pretty sure Frisk's a girl. In some routes, you go on dates with Papyrus and Sans, who we all know are boys.

You also obtain the Old Tutu and Ballet Shoes, and boys probably wouldn't want to wear that. Of course, some boys would, similar to how I'm a boy whose favorite color's pink, which is associated with girls.

Frisk's most likely a girl, but Chara's a whole other story, as we don't see many gender-associated actions and preferences of theirs. However, at the end of a soulless pacifist route (pacifist route after genocide), choosing to stay with Toriel plays a lower-pitched laugh at the end. This laugh most likely belongs to Chara, so Chara may be a boy.