Recently, my father said he wanted to take an Ancestry DNA test and asked me to order him one. Since this was something I'd been wanting to do myself for a while, I ordered two. We got the results back not too long ago and they were interesting to see. No, there wasn't any kind of family scandal -- my dad is my dad (and based on matches to an uncle and cousin, my mom is my mom.) What was interesting was the percentages that turned up. Knowing what I have uncovered about my father's side of the family, I had predicted he'd be mostly Irish with a bit of other British Isles thrown in since it would be unlikely he'd be 100% Irish. My predictions proved correct -- Dad's results came up 93% Irish (technically Ireland/Scotland/Wales) with a "very likely" connection to the Munster province of Ireland with "relatives who lived in this region in the past few hundred years." Dad's maternal grandparents were both born in County Cork which is part Munster, so that part is clearly correct. The rest of his test came up under "Low Confidence Regions" which showed the biggest chunk at 3% for Great Britain. So, yeah, my dad is Irish.

My "Low Confidence Regions" were a bit different than Dad's with 2% "Europe South" and 1% "Europe West" which is probably the French and German bits (though, oddly, Italy is the biggest land area for Europe South.) The fun stuff is in the trace amounts. Both Dad and I show up with less than 1% of Scandinavia (Vikings!), Dad comes up with less than 1% Middle East where I come up with less than 1% Caucasus which are overlapping regions and show the history of human migration.
The next task is to compare these results against other people who have taken the Ancestry DNA test to see if there are any relatives out there who might have more information on the family. There are a couple of promising results I've seen, but have yet to delve into them to see if they're worth pursuing.
Happy St. Patrick's Day!