In September 1943 Sneddon married Mary Campbell Macgregor, who he had known since his school days, in All Saints Episcopal Church in Jordanhill; they had a daughter and two sons:
Noong Setyembre 1943 Sneddon kasal Mary Campbell Macgregor, na niya kilala dahil sa kanyang paaralan araw, sa lahat ng mga Santo ukol sa mga ubispo Iglesia sa Jordanhill; sila nagkaroon ng anak na babae at dalawang anak: