John Sulston met Daphne Bate, a research assistant in Cambridge. They got married in 1966 just before they left for US for postdoctoral research. Together they had two children. Their first child, Ingrid, was born in La Jolla in 1967, and their second, Adrian, later in England. The couple lived in Stapleford, Cambridgeshire where they were active members of the local community: John regularly volunteered in the local library and in working parties at Magog Down; he was a Trustee of Cambridge Past, Present and Future.