ISO of my Father's birth parents or birth family

I'm searching for information regarding my fathers birth family. His adopted name was Samuel Lynn Stull. D.O.B 06-01-1944 in Hastings, Nebraska. Adopted parents names were Lee Hubert Stull and Lorene (Osborne) Stull. My father and grandparents are deceased and there are no living relatives alive that can provide any information. My father passed 12/04/2013 due to complications from ALS (Lou Gerhigs disease). One of the biggest regrets he had was not knowing where he came from. In addition to ALS my father also had Ulcerative Colitis which I inherited from him. I am curious to know which biological side of my fathers family this disease came from. My grandparents refused to give him any information regarding his birth and adoption other than my grandmothers sister was a nurse at the hospital where my father was born and she somehow arranged the adoption. The story was that my father's biological parents were young. Biological mother got pregnant and biological father went to WWII and was killed. If anyone out there has any family stories that sound familiar to this or have any information please feel free to contact me. God bless- Lori B.(Stull) Allen