Brad Wilcox of the Institute for Family Studies, who recently scoffed at “the notion that love, not marriage, makes a family,” has a forthcoming book titled “Get Married: Why Americans Must Defy the Elites, Forge Strong Families, and Save Civilization.” All of these scolds typically rely on the same batch of academic studies, now compiled by economist Melissa Kearney in her new book “The Two-Parent Privilege: How Americans Stopped Getting Married and Started Falling Behind,” which show that kids with two parents fare better on a variety of life outcomes than those raised by single parents, who are overwhelmingly women.