Is Justin Cronin related to A.J. Cronin?

No, Justin Cronin is not related to A.J. Cronin. Justin Cronin is a contemporary American author known for his works in fiction, including "The Passage" series, while A.J. Cronin was a Scottish author and physician famous for his novels in the early to mid-20th century. They share a surname but come from different backgrounds and eras.