Can Nick Trust Gatsby?

After the first few pages of chapter 4 of The Great Gatsby by F. Scott Fitzgerald, Gatsby begins to tell Nick more about himself.  The question is, can he be trusted?  "He looked at me sideways-and I knew why Jordan had believed he was lying...He hurried the phrase "educated at Oxford," or swallowed it, or choked on it, as though it had bothered him before....  I wondered if there wasn't something a little sinister about him after all (p 65)."  After this thought by Nick, I also wonder if Gatsby is telling the truth.  He tells Nick "I am the son of some wealthy people in the Middle West-all dead now (65)."  This seems to good to be true.  Gatsby offers no explanation as to how his family died, and the assumption that he has no family makes it easy for him to excuse the mystery of his past and makes it hard for Nick to inquire about it.  I'm sure Gatsby is hiding something, and Nick's intuition hear is merely foreshadowing the later reveal of these secrets.  Furthermore, Gatsby later mentions a "sad thing" that happened to him.  Could this be the reason he was staring out over the lake early in the book?  And why is he making Jordan tell Nick about it?   Then we find out he is friends with Mr. Wolfsheim, a gambler who fixed the World Series.  Gatsby claims to be and acts like a gentleman, but it is starting to seem like there is more than meets the eye when it comes to Gatsby.