Seth was the son of Daniel Comstock (1745-1814) and Patience nee Jenckes (1750-abt 1780). Daniel was born in Smithfield, Rhode Island and died in Lexington, Kentucky; his exact place of burial is unknown. Patience was born in Rhode Island and died in either Rhode Island or eastern Connecticut; her place of burial is unknown.
Seth was married to Mary "Polly" nee Arnold (1757-1858). Polly's place of burial is unknown; her father and stepmother are buried with Seth in the Arnold-Comstock cemetery as are some of her children. She is probably buried in this same cemetery but her marker is missing.