Do you think you're Irish?

According to this article, 12 percent of (US) Americans or over 36 million people claim to have an Irish ancestry. This is six times more than the current population of the Emerald Isle (there are 4.6 million people in the Republic of Ireland and another 1.8 million in Northern Ireland). This large number of Irish in America is far more than would be expected to occur.

How did 4.5 million Irish immigrants become 40 million Irish Americans? That's the title of an article by Michael Hout and Joshua Goldstein available from JSTOR.

Spoiler — their answer is an unexplained subjective "closeness" to Ireland choosing to associate with Ireland where they might have chosen another origin they's be equally as entitled to claim.