He was a member of what became a small dynasty of Scottish scientists and lecturers in analytical chemistry, which included, other than himself, his eldest half brother William Macadam, his immediate younger brother Stevenson Macadam (a younger brother Charles Thomas Macadam, although not involved as a scientist, was also indirectly involved in chemistry becoming a senior partner in a chemical fertiliser company) and nephews William Ivison Macadam and Stevenson J. C. G. Macadam, as well as the former nephew's daughter, his great niece Elison A. Macadam.