Iorwerth ap Cadwgon

Iorwerth ap was born about 1020 in Buillth, Breconshire, Wales.  Iorwerth ap's father was Cadwgon ap Elystan , of Buillth and his mother was Efa verch Gwrgan.  His maternal grandparents were Gwrgan ap Ithel , of Morgannwg and Nest verch Gwyn. He had a sister named Joan verch.  He was the older of the two children. He had a half-brother and a half-sister, named Idnerth ap and Constance "Wen" verch.

They had a son and a daughter, named Llewelyn ap and Dyddgu verch.