HELP!!! In the book....?

I believe every writer puts a bit of their own life experiences into their books. Haven't you ever heard of the phrase "write about what you know"? I am going to guess that Charlotte's sister, who wrote Wuthering Heights, is based off of her life maybe a little. It is said (or at least from what I have read through her poetry), that she had loved someone dearly that didn't work out. David Copperfield is suppose to be based on en's life,and considered his best work by himself. I believe A Child Called It, is based on the abuse the author recieved while growing up. (I think that is considered a novel, and not an autobiography). But if you read any novel, the writers are most likely writing about things they know, and usually they know about these things from their own life experiences. (Of course that would probably exclude fantasy and science fiction pieces!)