in 1816 he was wed to his first cousin, mary anne molson (1791-1862), daughter of thomas molson (1768-1803) of lincolnshire, england and anne atkinson (1765-1813). john and mary ann had five sons, including john molson iii who would later marry william molson's daughter and become a president of the molson bank, and a daughter. john died on july 12, 1860 at montreal.