My paternal line is McLain, anglicized of the gaelic "MacGillean". I've been doing DNA ancestry for quite some time and among hundreds of matches, only one name is recurring: "Galyean" and "Gallion" are several distant matches.
I was wondering if they had branched off of MacGilleans and maybe took the "Mac" off and had a variant spelling of Gillean. It seems from looking through a lot of the posts on this board of an Irish connection with settlers in the U.S. pre-1800, that your lineage may very well be a Scots-Irish one.
My most distant ancestor is Henry Macklaine, a Protestant Reverend in Dublin city in the 1750s. He is descended of the Clan Maclaine of Lochbuie, Scotland (I'm unsure of when exactly they came to Ireland) but my ancestors left Ireland in 1867 for New York.
Chris McLain Beal