Help, for a school project?

I've actually been researching this a little bit myself. The stereotypes bug me, and I'm trying to figure out how they started. One is that all lesbians are vegetarians. Also, that they always own a bunch of cats.

I don't know about the cats one, but the vegetarian one is possibly because lesbians don't eat "meat", so the word "vegetarian" became interchangeably used with lesbian, which made some stupid peope confused...I don't know, that's a complete guess.

well idiots think all lesbians are ugly and there NOT!! also people think all lesbians like every girl that walks by. so those are some stereotypes that i've herd. but idk where they originate from? sorry.

One of the most ridiculous ones I've ever heard is that female Gym teachers are all Lesbians. Not sure if this really applies to your study, but it's one that just bothers me. Not sure the origin of it, but maybe since Lesbians are stereotypically "butch" and all that, and since being a Gym teacher is a physical, tough job (a stereotypical job for a man), it kind of ties up with eachother.
I'm probably wrong, so if any knows the realy origin, please correct me. xD