Favorite Genres

At a writers' conference that I attended back in April, one of the speakers said that writers should pick a genre and stick with it. "Nobody wants to see a chick lit written by Stephen King," she said in way of explanation. Her comparisons were quite humorous, but I could see the point she was making. Writers become associated with the genre and style of writing they do. (I guess it must be the same for actors. For example, I would be very creeped out if I suddenly saw a new serious action thriller starring Will Ferrell.)
I think, for the most part, this idea only applies if you are already a successful, published author. I mean, if nobody but your friends, professors, and family have read your books, poems, or stories, why shouldn't you feel free to write whatever you like? Still, even if you do become successful and published, I think you should have the right to write what you like. Sure, your fan base will change, and marketing your work may become more difficult, but if the writing is superb, I like to believe that everything will work out eventually.
Of course, I'm still in the process. I do love to write in multiple genres, however. My favorite is young adult literature. I love the creative power that you can have with writing for that age level. It's just fun! Plus, as a high school English teacher, I am used to reading and writing YA lit. You can imagine yourself expanding their vocabularies and imaginations as you write your novel, nerdy as that may sound. I also love action and mystery. I recently started outlining a mystery series that I would love to write, and I can't get my ideas on paper (er, Microsoft Word, I should say...) quickly enough!
I think it's completely awesome to expand what you might consider your genre limitations. Don't be afraid to challenge yourself. What genres do you like to read? What ones do you write in?