Blancheflor of Beaurepaire calls him a very religious and saintly man, who has sent her the bread and wine which is all, with a deer newly shot by one of her servant, that she has to offer Percivale for supper.
Blancheflor is also Gornemant’s niece, so the prior might be Gornemant’s brother. If so, the frequency with which younger sons entered religion would suggest that Gornemant was the elder. I also see some possibility that, although Blancheflor praises her uncle Gornemant for being a very worthy, rich man, her contrast of the fine cheer he must lately have given Percivale with the poor fare that is all she has to give – most of it tanks to the charity of another and presumably less well-off uncle – might be constructed as a veiled complaint against Gornemant.
Against this interpretation we should weigh the fact that both Engygeron and Clamadeu fear to be sent prisoner to Gornemant because, in their war against Blancheflor, Engygeron has killed a(nother?) brother of Gornemant’s.