We have all heard about the sex gap in voting patterns. This is the phenomenon whereby, in every election, women are far more likely to support liberal candidates than men are. For instance, in 1996, Bill Clinton captured 54 percent of the women's vote but only 43 percent of the men's. And in subsequent elections, the male-female gap has been as follows: in 2000, Al Gore, 42-54; in 2004, John Kerry, 41-51; and in 2008, Barack Obama, 49-56. In fact, even in the watershed election of 2010, during which we heard about the rise of the conservative woman, the fairer...