The Welsh Triads giver her father as Afallach, a figure evidently connected to the island of Avalon. In Triad 70, Modron is the mother of the twins Owain and Morfudd by Urien Rheged. The triad seems to be connected to a story found in MS Peniarth 147 describing Owain and Morfudd's birth to an unnamed otherworldly woman. Here, Urien investigates a mysterious ford in Denbighshire where dogs went to bark. He find a washer woman, and has his way with her. She reveals that she had been condemned to wash at the ford until she conceived a son by "a Christian", and bids Urien to return at the end of the year to receive the child. On returning, Urien finds the twins Owain and Morfudd.