Write what you know, is something most of you have already heard. This seems to be a popular saying in the industry. I can understand that if you dive into a new culture and decide to write about it, or from it's PoV, things can get a little askew. But I still think that shouldn't top a person from doing it! Heck, it could shine some light on new and interesting perspectives. And the author would never do it unless he/she's researched it to bits. Any sensible author, that is. The "write what you know" just sounds restrictive and boring.
Write what you like! Heck yeah! There's no point in not writing something because you're afraid to "offend" someone, just because you got a fact or two wrong. So what? Most people read for the sake of a good story. And if you really like what you write, it will shine through.
Write what you read! I both like to write light fantasy and paranormal, because that's what I read. I'm trying to broaden my reading though, because I can well picture myself writing historical one day, dystopia, and even a sweet YA gay (I have an idea for a unique and fantastic one!). I even have an idea for a second contemporary (the gay one would be contemp. too), so I'm going to have to read some contemporary books in each genre to see if I like it enough to write it ;)
So, don't just write what you know - write what you like and write what you read :)
Picture source: http://blog.al.com/breaking/2007/10/pumpkin.jpg