I have written previously about how survey research underestimates the rate of gun ownership in the United States.
The main sources of “false negatives” (people who own guns but tell survey researchers they do not) are (1) people who don’t want outsiders to know they have guns, (2) people who want to avoid the stigma of gun ownership, and (3) people who cannot legally own firearms but do anyway.
Listening to my Sociology of Guns seminar students this semester has highlighted another group of non-gun owning gun owners. Of 16 total students in my class, 3 mentioned that their otherwise non-gun owning parents actually had guns in their homes.

Photo of family heirloom firearms from Sociology of Guns student