Born in Hiawatha, Kansas, to John Blanche McLendon Sr. (June 24, 1882 –October 15, 1973), a college teacher, and Effie Katherine McLendon (née Hunn; 1886 – 1918), one of his students at Washburn University. McLendon Jr. was part African American and part Delaware Indian from his mother's side. His mother died in the 1918 flu pandemic which would lead to the temporary break-up of his family. John and his younger brother Arthur were sent to be with his Delaware Indian grandparents on a ranch near Trinidad, Colorado while his older sister, Anita, was sent to be with an aunt in Omaha, Nebraska, and his younger sister, Elsie, was sent to be with other relatives, but would end up with a foster family on a ranch in Idaho. John would not see his younger sister again for 45 years, but the rest of the family were reunited after his father remarried in 1921 to Minnie E. Jackson, a school teacher in Kansas City, Missouri.