 He was a son of Virginia Reed (née Sturges) Osborn (1830–1902) and William Henry Osborn, a prominent railroad tycoon who served as president of the Illinois Central Railroad and, later, became a philanthropist who exposed the Boss Tweed ring.His older brother was Henry Fairfield Osborn, a paleontologist who served as president of the American Museum of Natural History for twenty-five years.His maternal grandfather was businessman and arts patron Jonathan Sturges.