Novels and non-fiction

Has anyone ever realized authors write about themselves when they write a book? In the beginning of every book, the author will open with a personal recollection or a mea culpa, to thin the crowd who will read it or invite the reader in. Any book lacking this set-up I immediately find suspect. I expect lying and truth-stretching from authors who do not intuitively introduce themselves off the bat as the first slice of information they start with in chapter one (the introduction usually does not count).