Dr. Guthrie had a personal interest in the prevention of disabling conditions. "It started with our second child, John. He is mentally retarded. John stimulated me to go into research aimed at preventing mental retardation and developmental disabilities." So begins his own treatise entitled The Origin of Newborn Screening. He never did find the cause of his own son’s disability. In addition to John, Dr. Guthrie’s niece had a developmental disability. She was diagnosed in 1960 with PKU as Dr. Guthrie was still developing his test.

Dr. Guthrie’s wife Margaret became very active in the creation of programs for those with developmental disabilities, beginning with the establishment of the Buffalo chapter of ARC (Association of Retarded Children, now The Association for Retarded Citizens) in 1954 when John was seven. She led the way in the establishment of sheltered workshops, group homes and other opportunities for persons with developmental disabilities. Dr. Guthrie and Margaret were founding members of Project RETAP, (Residences Employment Training Advocacy Public awareness for persons with developmental disabilities), which still operates for the benefit of the community in Western New York. The Guthrie family is known for their history of involvement in civil rights, human rights and disability rights.

If he hadn't been such a brilliant scientist, Dr. Guthrie might have been content to be a sailor. His passion began with rigging his own sailboats as a youngster, a hobby that he pursued throughout his life. When he was away working in places like New Zealand or Switzerland, he would take the time to glide along the water and relax. A favorite expression of his when parting or signing a letter was "Fair winds.” It served as a good luck charm to those lucky enough to have known this exceptional man and his amazing story of PKU detection, newborn screening and prevention.