I wasn't really surprised when I saw this headline:

"Irish ancestors of Kennedy, Reagan, Obama & Biden emigrated within 10 years of each other"

So many Irish emigrants during the Famine years! And now so many of their descendants in the U.S.! Why wouldn't there be a few Presidents among them?

Fiona Fitzsimons, who was commissioned to research the Irish ancestry of both President Obama and President-Elect Biden, has more to say on the subject of U.S. Presidents and their Irish heritage in this IrishCentral article.