Is There Always Autobiography in Everything You Write?

In early creative writing classes at school, most of us are told that you start writing about what you know. Is that fair? Or is there always a bit of autobiography in everything you write? Oh, there's always autobiography, and there's always experience. I think i was an over imaginative kid who loved stories, and i've grown up to become an over imaginative adult who still loves stories. It's very hard to answer that having not looked out of anybody else's eye. Except in fiction, which is the magic of fiction, it does let us look out through other people's eyes.