Nick questions part of Gatsby's life story because he finds inconsistencies in Gatsby's story. For example, Gatsby claims to have gone to Oxford, but Nick finds out that Gatsby never attended the university. Nick also finds out that Gatsby's real name is James Gatz and that he was born in North Dakota, not the wealthy family he claimed to have come from. These clues lead Nick to believe that Gatsby is not telling the truth about his past.
