cornyn was born in vancouver, british columbia. in 1922 he moved to los angeles where he first found work as a stock clerk, hall boy, and bookkeeper. he lived in san francisco from 1924 to 1928, working as an insurance clerk, eventually returning to los angeles. he married twice, first to sara ellen fetterman on 24 september 1928 (by whom he had son william, jr.); then to catherine mckee on january 29, 1937 (by whom he had two sons and a daughter).