The rationale developed that the nuclear family was optional; a successful happy family could be modeled with a single liberated woman. Men were superfluous after a certain point. “A woman needs a man like a fish needs a bicycle” was the inscrutable slogan.

Maybe, maybe not. Today, 40 percent of children in America are born to unmarried mothers, double the share in 1980. In the early part of this transformation, single mothers were likely divorced but now the majority has never married, and neither will their children.

Call it what you will but we have experienced an explosion of narcissism.

Those of us outside this social experiment were caught unprepared. All we had was anecdotal evidence as our warning. And we were conflicted by the fact that some of our best friends had been raised in successful families led by single, hard-working women, the widows of World War II. And the example of similarly exceptional women has continued over the years.

Looking back, though, we understand that those women made clear to their sons and daughters that the family would need to make a heroic effort to make up for their loss — a far different approach than today’s signaling that men are dispensable or at least interchangeable.

But again, we didn’t have data. Now we do. Economist Melissa Kearney has written “The Two-Parent Privilege: How Americans Stopped Getting Married and Started Falling Behind.” This carefully researched work ends a half century of debate. Here is Kay Hymowitz’s review in the this month”s City Journal:

“Growing up apart from a father carries considerable risks for children aside from economic hardship. Boys, in particular, are more likely to have academic and behavioral problems without their fathers in the house, and, statistically speaking, the presence of a stepfather doesn’t make their futures look any rosier. Growing up in a single-mother household is associated with poorer college completion, even after controlling for a host of other variables, as well as with diminished likelihood of marrying or staying married upon reaching adulthood.”

And no, the government cannot come to the rescue. There is evidence in the Kearney statistics, charts and models that even in the most progressive utopias government benefits do not compensate for family structure. It is a point of perverse pride that Indiana, with low welfare benefits, scores 46th in a list of best places to raise a family as a single parent.

“To marry is both to enter into and to create a family — the most powerful community in which most individualistic will ever engage — and to connect to a supporting network of friends, extended families and neighbors,” Kearney writes. “Family breakdown on the scale that we’ve seen in past decades inevitably ruptures communities and social life.”

Hmm, do we need to point out that similar warnings have been posted in scripture as well as in every other religious tract throughout the world, not to mention being hard-wired in cultural mores and taboos dating back to prehistory? Inconvenient though it may be, and how much our hearts may ache for struggling moms and adrift children, marriage between a man and a women seems to be the way human society is made to work.

They say you are wise when you have seen two generations make the same mistake. The single-parent family is that mistake.

Craig Ladwig is editor of the quarterly Indiana Policy Review. Send comments to [email protected].