Born in Turin, Thomas Francis was the youngest of the five legitimate sons of the sovereign Duke Charles Emmanuel I, Duke of Savoy by his consort Catherine Micaela of Spain, a daughter of King Philip II of Spain and the French princess Elizabeth of Valois.
The fief of Carignano had belonged to the Savoys since 1418, and the fact that it was part of Piedmont, only twenty kilometers south of Turin, meant that it could be a "princedom" for Thomas in name only, being endowed neither with independence nor revenues of substance [REF].