That's gay?

I was watching Family Guy last night and one of the brand new episodes was playing. In it, Peter gets an injection at the doctor's office that turns him gay, dubbed the "gay gene." After said injection, Peter starts baking muffins, wearing tight clothing, dancing out at dance clubs late at night and so forth. Eventually, he leaves his wife for another man. While I was watching this episode, I began to wonder. Why does baking muffins make Peter gay? Why does it make him gay to wear a lime green shirt? Or to dance out at a club late at night? Many of the traits Peter expresses in the episode after turning gay are traditionally feminine traits. This led to another question for me. Why are gay people represented this way? Why is it that in any typical movie that features a gay male or female are the traditional gender traits transposed? Lois suspects that Peter is gay when she sees him baking muffins, a typically feminine thing to do. This is not the first of television shows or movies that make gay men extremely feminine and gay women extremely butch. Does this reflect real life? Not totally. Take a look at Ellen DeGeneres and Portia de Rossi. Ellen is more of a masculine figure in the relationship with her short hair and her white pantsuit at their wedding. Portia, on the other hand, wore a beautiful white gown, she wears high heels often, has long bonde hair, and is a pretty feminine woman. Or my sister, for example. She is a lesbian but she is not overly manly at all. She has long hair, loves to wear pink, and just acts like herself or any other person. These are just a few of many real life examples in which gay couples' gender traits are not being transposed. So why then, if this is true, do television shows and movies make gay men seem really girly and gay women seem really manly?