Irish?

Until a couple years ago, I thought my family had Irish ancestry. Regan is not an uncommon Irish surname. Certainly my original Regan immigrant ancestor was Irish. I stand corrected. My great-grandfather changed our last name from Regnery to Regan, which is German. I'm not certain why he changed his name, my Dad said that his father didn't talk about it much. There could be a variety of reasons, and I don't dare presume what his was. So, unfortunately I can't wear a "Kiss me I'm Irish" button today, but I am wearing green. And we will be having corned-beef and cabbage for dinner tonight.