Nice! Of course no body knows how the Joker really became the way he was. Whether he was a gangster or some comedian forced to work with them. It's part of his mythos that we have no idea of his past, really.
I never liked the whole him falling in to chemicals thing, it's to plain for him. The Joker is such a complex character that I believe his real origin should never be told, thats why I liked the way Nolan did Ledger's Joker