On my bookshelf is a picture book from 1980 that tells children how babies come into being. The text says, “Since a family is happier with children, your mother and father wanted a baby. They wanted you … to love and to care for.” Thirty years ago, it was normal to assume that getting married and having children made life better. In 1980, 33% of women had four or more children. Childlessness was rare, and the childfree movement unheard of. Now, approximately one third of millennial an...