Cormac was born in 1411, the eldest son of
Teige MacCarthy. His father was the 6th
Lord of Muskerry. His father's family were the
MacCarthys of Muskerry, a
Gaelic Irish dynasty that had branched from the
MacCarthy-Mor line in the 14th century when a younger son received
Muskerry as
appanage. Nothing seems to be known about his mother, not even her name. He had a younger brother Dermod, ancestor of the MacCarthys of
Drishane, and a sister Ellen, married first
Donal MacCarthy Reagh, Prince of
Carbery, and then secondly Eoghan of Rathduane. == Marriage and children ==