Certainly from Norman times onward, but likely prior to that as well, there has been the expression of various newcomers (invaders) becomming "more Irish than the Irish themselves". Depending on the observor, that could/would be said as either a compliment or epithet. At the usual risk of speaking in general terms, the Irish people tend to be a gregarious and genial lot, and their culture reflects that. The inverse relationship is probably also true to some extent. I hasten to add that the same can be and should be said for many other cultural/ethnic groups around the globe. There's likely more than a few theses, dissertations, books, symposia, etc, etc lurking within any serious exploration of the whys of such things.