It'll be Patty. She's been turned down by every man she's ever been with and when a lesbian comes on to her in a bar she turns to women.
That's what these people say. There's other sugesstions but this one is in depth and has a source. http://amptoons.poliblog.com/blog/001167.html
(note sort of a small bit of spoillers if this is true considering i might have given away too much already)