On St. Patrick’s Day, everyone is Irish. Maybe just for the moment, or for the next few beers. O’Hara, O’Leary, O’Bama. But some of us have real, biological connections to the Emerald Isle. One of the reasons I was delighted to make a trip to Ireland last year was the chance to close the circle. By a happenstance the year before, I found the oldest proof of my European ancestors. On the Internet I stumbled across the website of the Compass Inn in Ligonier, Pennsylvania. What became the Compass Inn was built as a log building in 1799 on the...