Board Thread:General Discussion/@comment-27907368-20160412010659/@comment-27907368-20160421004334

Yossipossi wrote: My sister pointed this out to me: Somewhere in the game, it says "she" when refering to Alphys, confirming it's a girl.

Not so sure about Undyne tho. Undyne is definitely a girl. I believe PAPYRUS calls her a she as does Monster Kid. What comes to mind first is the "Oh, you're going to see her too!" line from Monster Kid. ^^