lorcán was born at kilkea, ireland, the youngest of four sons of an o'byrne princess and muirchertach ua tuathail. the family were of the uí muiredaig branch of the uí dúnlainge kindred and took their name from tuathal mac augaire, king of leinster, who died in 958. they resided at maistiu (mullaghmast) in what is now county kildare.