Yes, but I reckon the trans-Atlantic people were very much the minority. It is surely the case that most came from Siberia via the Bering Straits. That is clearly where we see very great similarities in ethnic characteristics, clothing, housing, religion. I have just read a book on native Siberians (the Ruskies treated them every bit as badly as the Yanks did the American Indians) the photograpghs are indistinguishable from photos of American Indians. There is the tantalising enigma of Kennewick man still to be resolved and the Native Americans are opposed to archaeology that disturbs the ancestors. They will be even more reluctant if it can be shown that they were not the ONLY First Nation

The story of St. Brendan and his trip to the Americas was actually on my history course when I was in school. I read an article a few years ago about the similarities between Gaelige and a certain Indian language (can't remember which one) the only example I can remember at the moment is "uisce" means water in Gaelige. Water in whatever Indian language it was, was "uiske". I should look that article up again I think it was it "The Irish Times" will get back to you if I find it.