He was born in Belfast in 1935 and studied medicine at the Queen’s University of Belfast (QUB). After graduating in 1957, he took a series of appointments in the Royal Victoria Hospital and QUB. In 1965 he was appointed to a Medical Research Council Clinical Fellowship at the Clinical Genetics Research Unit at the Institute of Child Health in London and Great Ormond Street Hospital. Here he was to develop a lifelong interest and expertise in the field of genetics which was at that time a fledgling discipline.