But among low-education, low-income whites, as well as blacks and Hispanics, family disintegration has become the norm.

Will these trends go on forever? Not necessarily. Schulz looks back to the 1950s, years of unusually high marriage rates. Go back further, to the years around 1900, and Americans were marrying later, and larger percentages than today never married at all.

Increasing affluence and changing mores reinforced by universal media such as movies and television helped produce the mid-century America with well-nigh-universal married parenthood.

People learn from experience. In surveys, children of divorce express disapproval of divorce — and the decline in divorce rates since the 1980s suggests they divorce less often than their parents’ generation did.