The texts of Welsh laws which survive until today were written down starting with the 12th century, but they provide no evidence that women were capable of transmitting legal title of kingship or lordship.
Equally, although Rhodri's pedigree in a manuscript in Jesus College Oxford[5] states Nest as his mother, another pedigree in a fourteenth-century manuscript[6] in the National Library of Wales records his mother as Essyllt ferch Cynan.
There are no strong grounds to accept either manuscript as reliable, but it is reasonable to believe that the royal house of Gwynedd promoted the view that the Kingdom of Powys had passed to Rhodri the Great through his mother in order to legitimise their control over it.
Consequently, those taking this view conclude that Nest's alleged marriage to Merfyn (or Rhodri) was merely a rumour spread and recorded by supporters of Gwynedd to demean the Kings of Powys and to claim lordship over them.
The House of Gwynedd's Kingship is recorded being passed jure uxoris through Essylt to her husband Merfyn and thence distaff (i.e. by the female line) to their son Rhodri on Merfyn's death, the same going for Rhodri's wife Angharad, the daughter of Meurig King of Seisyllwg when her brother Gwgon drowned without an heir, allowing Rhodri to rule Seisyllwg jure uxoris and his son Cadell to inherit it matrilineally.