Kevin, son of Cornelius Cronan and Agnes (nee Lockhead), was born in Melbourne and grew up in the suburb of Highett. He had one brother, Barry. Kevin was educated at Christian Brothers College at St Thomas, Clifton Hill and Parade College, East Melbourne. Kevin excelled at academic work, winning many school prizes.

When Kevin completed school in 1960, he was awarded a Commonwealth Scholarship. He studied medicine at the University of Melbourne, completing Bachelors degree in Medicine and Surgery in 1966. He worked as Junior Resident Medical Officer and Senior Resisdent Medical Officer at St Vincents Hospital, Melbourne from 1967 to 1969. He joined the staff of the Austin Hospital as Clinical Pathology Registrar in 1969, and became Haematology Registrar there from 1970 to 1971, and Senior Medical Registrar from 1971 to 1972. In 1969, he was awarded the Prize in Forensic and Legal Medicine by the Royal College of Pathologists of Australia, and became a Fellow of that College in 1974.

He moved to Prince Henry Hospital, Sydney as Senior Fellow in Haematology in 1972, then in 1974, became the Director of the Blood Bank in Newcastle NSW. Due to work pressures he became semi-retired in 1975, and continued to work as a consultant and lecturer in medicine and pathology.

Kevin was a keen sportsman thoughout his school years. He enjoyed swimming and tennis, and his love of these sports continued thoughout his life. He also had strong interests in writing and philosophy, and returned to the University of Melbourne later in life to study philosophy. Kevin valued highly the rights of the individual, privacy and human rights. He was concerned with medical ethics and social justice.

Kevin married Felicity Stead in 1967, and had one son, Justin, born 1971. Felicity and Kevin remained married until his death. He also had a close relationship with his parents, meeting them once per week for lunch. Kevin died very suddenly of a brain aneurysm on the night of 25 October 1995, and in accordance with his wishes, his organs were donated.