one source says mac creiche's father was pesslan (not an irish name) and his mother was from the cíarraige people. it is possible that the corcu modruad were subordinates in an alliance led by the cíarraige. another source says he was of the fermacaig, and the son of saint ailbe of emly. the sources agree that he was connected to the cíarraige. he may have been a cousin of saint brendan of clonfert on his mother's side. mac creiche is said to have lived to 180 years of age, which would make him one of the oldest of the irish saints.