Earlier this week Jeb Bush announced he was setting up a political committee to explore a presidential candidacy. Hillary Clinton has been exploring a presidential candidacy for months and perhaps years. Polls show Clinton with a wide lead for the Democratic nomination and Bush as a leading competitor for the Republican nomination. All of which leaves many people, some of them admirers of one or both potential candidates, queasy. Out of 319 million people in America, will our 45th president be the son of the 41st and brother of the 43rd or the wife of the 42nd? The United States...