 Kielhofner's work is widely cited and his model stands among the most influential theoretical contributions in the history of occupational therapy.Gary Wayne Koehofner was born in Cape Girardeau, Missouri on February 15, 1949 and lived in rural SE Missouri (Oran) during his boyhood.His early schooling was in nearby Chaffee, Missouri at St. Ambrose School in the Catholic parish of the same name.