Stephen was the eldest son of András Báthory and his wife, Margit Majláth.
[3] Before the end of the year, his mother married János Iffjú, and moved to her new husband's estate in Érmihályfalva (now Valea lui Mihai in Romania) along with her four youngest children.
[3] Stephen and the eldest of his four brothers, Gabriel, stayed behind in the Báthorys' castle in Szilágysomlyó (now Șimleu Silvaniei in Romania).
[7] She was descended from an aristocratic family, but the marriage outraged Stephen's royal uncle.
[10] Stephen's conversion from Catholicism to Protestantism further worsened his relationship with his uncle, but he soon returned to the Catholic faith.