His paternal family seem to have borne the name Simonde, at least from the time when they migrated from Dauphiné to Switzerland at the revocation of the edict of Nantes. It was not till after Sismondi had become an author that, observing the identity of his family arms with those of the once flourishing Pisan house of the Sismondi and finding that some members of that house had migrated to France, he assumed the connection without further proof and called himself Sismondi.