From what I've been told, my Guerin family has been quite nomadic. Recent generations are from western Massachusetts who came down from Quebec around the turn of the century. Their ancestors came from France, Normandy region. My family has always identified with the French background, however my grandfather recently told us that prior to France, Guerins lived in Ireland. When looking around online, it is a fairly common name in Ireland, and I've had many Irish people tell me that it is an Irish name. One such person told me about the "Flight of the Wild Geese", which was when the Guerins and many other Catholics fled Ireland when the Church of England attempted to drive catholics out of the country. ?1600s? They fled to other catholic european countries, such as France and fought in the Irish Brigades. This is a very anecdotal story, but some of it checks out with some informal internet searching. I hope this helps!