It was 1986, I think, when I went to Ireland with my wife, to meet her family.

We flew into Heathrow, and made the long trip to the Aer Lingus terminal. Finally we found it, and as we stepped inside, Michele exclaimed,

"Will ya look at all the Paddy faces!"

And in the blink of an eye, looking at the tableau of waiting passengers, I saw the Irish as three major tribes: The aforementioned primordial Celts, the blondish Vikings, and the dark-haired descendants of castaways from the Spanish Armada, the Black Irish.

It's an oversimplification to imply that's all there is to Irish genetics. For one thing, the Irish have been wanderers for a long time. They flee harsh conditions, sometimes stay away for generations, but eventually the genes flow back, bringing along an infusion of mingled genes.

It's really their culture that unites the Irish, anyway. Nothing strengthens the tribe like the oppression of the British and the contempt of prior-arrival Americans. It took 800 years to make the Irish. They're strong.