There are some theories that the Gael's originated from the Basque shelter and are not even of Indo-European decent, however their language originated from later invading tribes from central Europe who were more advanced and dominated (possibly of Asia Minor origin). Did they all belong to the same ethnic group (Celts)? For those who don't understand "ethnically distinct", I mean could they be distinguished by shared physical characteristics of face, height or otherwise?

Context Explanation

Did a Gael look like a Briton or a Pict? I can't find anything relevant from my preliminary research.