A good orientation to the problem of trusting medieval Irish genealogies. Don’t make the mistake of copying what you find online. It’s all very interesting, but it’s not vetted genealogy.
Donnchadh Ó Corráin, “Creating the Past: The Early Irish Genealogical Tradition” in Chronicon 1 (1997) 2: 1-32.
ABSTRACT: Traditionally Irish early medieval genealogies were seen as the product of oral tradition, recorded at an early period by monastic writers. This is mistaken. No doubt there was an oral genealogical knowledge, but the genealogical record is modelled on the Old Testament genealogies.