I don't know if he had siblings. That's where the major problem comes in, I guess. His death certificate says his father was Jas (or Jos) Brooks and his mom was Frances Milburn. A family Bible said his father was James Armistead Brooks, a circuit-riding, red-haired Baptist preacher who separated from his first wife, Frances Heatherly. The Bible indicates she's John William Brooks' mother.
I'm not finding records using combinations of any of those names. And, of course, the 1890 census isn't available.