Joanna was the daughter of unknown parents. The date and place of her birth have not been found.
Her husband was Donal Glas MacCarthy. They were married, but the date and place have not been found. Their five known children were Donogh (?-?), Dermod an-Dunaidh (?-?), Donal Glas (?-?), Eoghan (?-1442) and Cormac na-Coille (?-?).