His mother, Annie Burnett Duncan, was a schoolteacher, and his father, Alexander Mackie, was professor of education at the University of Sydney as well as the principal of the Sydney Teachers College, and was influential in the educational system of New South Wales.
Jego matka, Annie Burnett Duncan, była nauczycielką, a ojciec, Alexander Mackie, profesorem edukacji na Uniwersytecie w Sydney, a także dyrektorem Sydney Teachers College, który silnie wpłynął na system edukacyjny Nowej Południowej Walii.