Hont County
Stephen was born into the "gens" Csák as one of the four sons of Matthew I, founder and first member of the Trencsén branch, who served as master of the treasury (1242–1245), and Margaret from an unidentified noble family. Stephen's brothers were Mark I, ispán ("comes") of Hont County in 1247, but there is no further information about him; Matthew II, a notable general and palatine of Hungary (1278–1280; 1282–1283); and Peter I, who also held powerful positions, including palatine (1275–1276; 1277; 1278; 1281) and who, furthermore, was the father of the notorious Matthew III. He had also a younger sister, who married to the Moravian noble Zdislav Sternberg, a loyal bannerman of the Csák clan. Their son, Stephen Sternberg (or "the Bohemian") later inherited the Csák dominion because of the absence of a direct adult male descendant after the death of Matthew III in 1321.