Self was born in Hamilton, Montana, USA, on 14 August 1909 (claimed 17 August), as the youngest of nine children born to parents Walter Leonard Chesnutt (1855–1933) and Susan Alvina Campbell (1869–1949). Her siblings were: Lessie Marie Harris (1891–1953), Grace Willie Jones (1892–1986), Booth Chesnutt (1893–1963), Eunice Frances Donaldson (1895–1967), Ella Irene Howard (1898–1967), Walter Chesnutt (1900–1965), and Joseph Chesnutt (1906–2007). She was raised in the Bitterroot Valley, where she attended a school in Grantsdale. Throughout the 1918 flu pandemic, she and her brother Joseph would visit neighbors and run errands. At the age of 12, she relocated to Missoula to reside with her sister Lessie and began attending a school in the area.