Duffy grew up in Garrett Park, Maryland, a suburb of Washington D.C. He cites the death of his mother by medical malpractice when he was eleven as the trauma that drove him to be a writer. His first novel, The World as I Found It, was called one of “five great nonfiction novels” by Joyce Carol Oates. He received a Whiting Award and a Guggenheim Fellowship in the year following the novel’s publication. He has also contributed to Harper’s Magazine, Time Magazine and Life magazine, among others. He currently lives outside of Washington, D.C. with his wife, who is a psychotherapist.