on april 25, 1905, hawkes was married to suffragette alice silliman belknap (1878–1972) in louisville, kentucky. alice was the daughter of william richardson belknap, the president of the belknap hardware and manufacturing company, and alice trumbull (née silliman) belknap. her paternal grandfather was william burke belknap and her maternal grandfather was benjamin silliman jr., a professor of chemistry at yale university who was instrumental in developing the oil industry. among her siblings was the artist eleanor silliman belknap humphrey and william burke belknap. together, they lived at 124 east 65th street and were the parents of: