Cowan was born on 2 August 1861 at Glengarry, a sheep station near Geraldton, Western Australia. She was the second child of Kenneth Brown, pastoralist and son of early York settlers Thomas and Eliza Brown, and his first wife Mary Eliza Dircksey Wittenoom, a teacher and the daughter of the colonial chaplain, J. B. Wittenoom. Edith's mother died in childbirth in 1868 when Edith was only seven.