Their mother, Marta (Koch), is a modern dancer. Their father, Robert S. Miller, worked for Hyperion Books, and is a publisher at Workman Publishing. Ezra's mother is of three quarters German and one quarter Dutch ancestry, while Ezra's father is from an Ashkenazi Jewish family (from Germany, Russia, and Austria). Ezra's father's step-brother is a rabbi, and Ezra's father's step-nephew is writer Gideon Lewis-Kraus.