looking for son born 6-6-1966

I am looking for my son who was born at Sioux Valley Hospital on April 6, 1966 in Sioux Falls, SD. He was placed for adoption with Lutheran Social Services. I received a letter stating that his adoption was placed through the Rapid City Lutheran Social Services six weeks after birth. I do have some medical problems that could possibly be hereditary. I would like to let him know that I've been praying for many years for him. The name I gave him is Robert Eugene, after his birth father. I was 16 at the time of his birth.