Despite its attachment to a version of Geoffrey's work, it is clear that Geoffrey did not use the Mostyn genealogy, as he has Constantine (Custennin/kustenhin) as fourth in line from Conan (Cynan/kynan) which the Mostyn does not*. This suggests he used a genealogy similar to the Jesus Gen. XI, which, combined with later versions, gives*...

Gereint son of Erbin (son of Custennin) son of Kynvawr son of Tudwawl son of Gwrwawr [erroneous "son of (G)adeon" as he was Cynan's brother] son of Cynan son of Eudaf Hen

He then connects Arthur with the famous military leader of about the right time, Custennin.

The general level of completeness is better in the Mostyn manuscript and, assuming no editorial input in the published sources, it looks like it contains an older set of name-versions (e.g. Tutwal for Tudwawl). However, despite this, the presence of Arthur; the obviously mythographic nature of the early section of the genealogy; and the association with Geoffrey, has led most commentators to regard the Jesus genealogy as closer to reality and less contaminated by Geoffrey's thinking (for example, Kirby*; Pearce*).