Question: Were Stewart O'Nan and John O'Hara of the same nationality?  
Sentence (from "John O'Hara"): John Henry O'Hara (January 31, 1905 – April 11, 1970) was an American writer, best remembered as a keen observer of social status and manners in early to mid 20th century America and pre-eminent among his contemporaries at depicting social realism.
Relevant evidence: Yes