When Robert Ewing Duncan was born on 27 March 1903, in Hampshire, Maury, Tennessee, United States, his father, Oscar Dayton Duncan, was 25 and his mother, Aquilla Ophelia Peery, was 26. He married Alice Jossephine Morrow on 7 January 1926, in Maury, Tennessee, United States. They were the parents of at least 1 son and 3 daughters. He lived in Civil District 1, Lewis, Tennessee, United States for about 10 years. He died on 28 December 1953, in Columbia, Maury, Tennessee, United States, at the age of 50, and was buried in Brown Cemetery, Lewis, Tennessee, United States.