After graduating BAgrSc in 1963, it was assumed he would head back to assist on the family farm, but he was encouraged to undertake further studies at the University of Melbourne. Cotton began his career in the field of biochemical genetics with bacteria and the synthesis of amino acids, the building blocks of proteins, completing his PhD at the University of Melbourne in 1967. He was a postdoctoral fellow at some of the leading human genetics laboratories in the world, first at the John Curtin School of Medical Research at the Australian National University in Canberra, and then overseas at the Scripps Clinic and Research Foundation in southern California, and the Laboratory of Molecular Biology at the University of Cambridge. He graduated DSc from the University of Melbourne in 1983.
