It Takes Two

Does The Two-Parent Privilege get it right?
Of all the sources of unequal opportunity in the U.S., family structure is unique in the discomfort it causes analysts and policymakers. Yet it is critical to our understanding the lived experiences of American children and how policymakers can support their health and well-being.

It is indisputable that children are better off living with two nurturing parents who are in a stable, loving relationship compared to any other living situation. But it gets more contentious from there. Does “stability” require marriage? How important is it to live with two biological parents? What if one (or both) adults are not in love or are negative influences on their children? These questions matter, because, in the real world, the alternative to children living with a single parent is not always two nurturing, married, biological parents who are in a stable, loving relationship.

They also matter because the likelihood that a child lives with married parents has fallen markedly. In 1980, 77 percent of children in the U.S. lived with married parents. By 2019, just 63 percent did. About one in four children live in a single-parent home—for the most part, with single mothers.

The rise in single motherhood has been driven by nonmarital births, not divorce, and is concentrated among disadvantaged women. Only 12 percent of children whose mothers have graduated college live with a single mom, compared to 30 percent of children whose mothers did not graduate high school and 29 percent of children whose mothers do not have a college degree. There are stark racial differences in rates of single-parent families as well. Some 54 percent of Black children live with a single mother compared to 15 percent of white children. A Black child whose mother has a college degree is as likely to live with a single mother as children of other races whose mothers lack a high-school diploma.

These numbers come from an important new book, The Two-Parent Privilege: How Americans Stopped Getting Married and Started Falling Behind, by University of Maryland economist Melissa S. Kearney. The decline in marriage she documents is even more pronounced than her figures suggest (see Figure 1). The deterioration of the two-parent family was well underway by 1980, beginning at least as far back as the late 1960s. Kearney’s view on how we should interpret this decline, and her reason for writing the book, is stated clearly in the preface:

Based on the overwhelming evidence at hand, I can say with the utmost confidence that the decline in marriage and the corresponding rise in the share of children being raised in one-parent homes has contributed to the economic insecurity of American families, has widened the gap in opportunities and outcomes for children from different backgrounds, and today poses economic and social challenges that we cannot afford to ignore—but may not be able to reverse.

This statement is more controversial than it should be. Of all the sources of unequal opportunity in the U.S., family structure is unique in the discomfort it causes analysts and policymakers. As Kearney notes often, the subject is taboo in many circles, and raising it opens one up to charges of stigmatizing single mothers and their children. Already, she has been subjected on social media and left-leaning corners of the Internet to the judgmental motive-questioning criticism of self-ordained defenders of the poor.

Yet these questions are critical to our understanding the lived experiences of American children and how policymakers can support their learning, health, and well-being. Should policymakers invest in programs designed to nudge parents to marry or stay married? Or, if the traditional two-parent family structure is in inevitable decline, what programs should we support in its stead?

Figure 1: A Decades-Long Decline in Married Childrearing

Causes and Consequences

For what it’s worth, a majority of parents from a variety of family structures seem to agree that marriage is important for kids. A 2007 survey by the Pew Research Center, the most recent I could find with analyzable data by different family structures, asked, “When an unmarried man and woman have a child together, how important is it to you that they legally marry?” The share of mothers aged 18 to 44 saying “very” or “somewhat” important (as opposed to “not too” or “not at all” important) was 73 percent among married, separated, or widowed mothers, 56 percent among divorced or cohabiting mothers, and 56 percent among never-married mothers.

Nevertheless, Kearney’s statement is quite strong. What can we say about the substantive case made by her critics? No one disputes the evidence that Kearney (pretty cursorily) reviews showing that across a large variety of outcomes, in hundreds of studies, children who grow up with a single parent or who experience family disruption do worse than children in stable two-parent families.

For instance, one review of 47 causal studies of family structure shows that in the area of education, children living with two married parents have higher test scores and educational aspirations. They have fewer behavioral problems at school, are more likely to be prepared for class, and are less likely to be held back. Children from two-parent homes also are more likely to graduate from high school, enroll in college, and earn a degree. One especially rigorous study comparing the educational outcomes of children of identical twins—one divorced, one not—found that experiencing a parent’s divorce before age 16 reduced educational attainment by one-fourth of a year, on average.

Critics question whether these unequal outcomes are in fact caused by differences in family structure. This may seem like an easy question to answer, but thinking about specific real-world families reveals the methodological challenges to be tougher than may be apparent. Single parenthood is not distributed randomly. It may be that the kids of single parents would do even worse had their parents gotten or stayed married. For example, some parents may be abusive.  

Very few statistical analyses can account for such scenarios (see sidebar: “A complex research question”). And in my view, Kearney gives somewhat short shrift to these analytical challenges, though she concedes a lot more than her critics have suggested. However, this is a methodological point. As Kearney rightly suggests, it defies reason to think that the historic increase in single motherhood reflects a historic increase in the number of families for which single motherhood is better for kids—or that single parenthood was always better for one in four kids, and we’re fortunate today that more families choose it. For that matter, there are sophisticated studies exploiting “as good as random” variation in family structure that find negative effects.

But let’s back up. Children of single parents have worse outcomes than children living with married parents, on average. Therefore, when skeptics of family-structure studies argue that the counterfactual of having married parents would be worse (or no better), they are really saying that the children of single parents are doomed to lousy outcomes, no matter what. So even if the skeptics are right, the rise in single parenthood constitutes a crisis.

We owe children a better start in life. And that means ensuring that more children are born into likely-to-be-successful parental relationships instead of relationships where they are doomed to lousy outcomes. And as Kearney emphasizes, the parental relationships most likely to succeed will involve marriage, which entails some combination of a symbolic shared identity, religious covenant, and legal commitment device.

A Complex Research Question

How do researchers assess the causes and effects of single parenthood? As Kearney notes, the gold standard in research is a randomized controlled trial in which there is a very specific “treatment” given to one group and withheld from another. This is how new medicines are tested: people are randomly assigned to receive either a drug or a placebo so researchers can be fairly confident that any difference in outcomes between the two groups was due to the treatment. While the exact causal effect of the treatment might vary from person to person, we can estimate the average causal effect across all people in the treatment group of getting the treatment.

Since we can’t experiment on people by manipulating their family structure, we have to rely on survey data and statistical methods that, as best they can, mimic a randomized controlled trial. But there are many problems with this alternative. First, “single parenthood” is a hopelessly vague “treatment” when compared with something like a specific pill administered in a drug trial. Using something like “having lived with a single parent” as the treatment of interest is more like giving each member of the treatment group one of any number of pills that are sort of alike.

Even if the treatment is defined more narrowly—such as “experiencing parental divorce”—the problem is that context matters in a hundred different ways we can’t observe. Kearney’s own, very clever, research hints in this direction. She shows that the “effect” of being born to married parents rather than to a single mother depends on how much education a mother has and on the outcome under study.

But admitting that the answer is “it depends” opens a giant can of worms. If a divorce occurs because a woman in an outwardly well-functioning marriage discovers her husband has had an affair, the effect on the kids is likely to be very different from the effect of a divorce after years of parental discord. These are, for all intents and purposes, different treatments.

Moreover, in the real world people make choices or experience conditions that determine whether they are in the “treatment” or “control” group when it comes to single parenthood—it’s not like a randomized controlled trial where the two groups are the same on average, save for the treatment they get. The treatment group is likely to be different from the control group in myriad meaningful ways, even after statistically taking account of gross demographic and economic factors.

Complicating matters more, many will have self-selected into the treatment or control group based, in part, on what they think is best for their kids’ outcomes. It’s as if people in a drug trial had a decent sense of whether they’d be better off taking the pill or not and then chose for themselves what group to assign themselves to.

At the extreme, if everyone acted in their children’s best interests and had perfect information about what would be ideal in their specific circumstances, then the effect of single parenthood would be positive for the children of single parents and negative for the children of married parents. But it’s unlikely that survey data analyzed with statistical methods would correctly suss that out.

Given these methodological problems, the best we can do is to find “exogenous” (or “as good as random,” as Kearney nicely puts it) variation in family structure caused by a specific shock that affects only specific people. Then, through advanced statistical techniques, we can identify the effect of the family structure change caused by the shock on the subset of kids whose families changed. And even then, we must be wary of generalizing about the “effect of single parenthood” beyond the change caused by this specific shock affecting this specific subgroup.

In short: it may be more challenging than Kearney implies to establish the average causal effect on a child of experiencing single parenthood. That does not, however, imply that the true average effects are positive or nil.


The Trouble With “Marriageable Men”

How do we create the conditions that foster successful marriage? Kearney’s policy proposals are heavily influenced by her diagnosis of how we got here. Broadly speaking, researchers debate whether economic factors, cultural factors, or policy choices have driven the marriage decline. Kearney devotes the most attention to economic explanations and lands in favor of improving economic conditions for men.

She embraces the “marriageable men” hypothesis first elaborated by sociologist William Julius Wilson in the mid-1980s. According to this view, single motherhood has risen because men have done increasingly worse economically, making them unattractive as husbands. It’s not so much that single women are having babies at higher rates than in the past (though they are), but rather that more of them are single—and therefore at risk of having a nonmarital birth—because the men on offer are not doing well.

The problem with this explanation is that men’s hourly wages and annual earnings are at or near all-time highs. Pay for the lowest-educated half of men stagnated or declined over a long period from the early 1970s to the early 1990s. But since then, pay has risen appreciably—median male earnings are up by 33 percent since 1979, even after adjusting for the increased cost of living.

Kearney emphasizes the disappointing trends for men with the lowest levels of education. But looking at earnings trends by education level leads to inaccurate impressions. Educational attainment has risen. Men without a high school diploma, for example, constituted 30 percent of men in 1973 but just 10 percent of men in 2019. Comparing the economic outcomes of the bottom 10 percent of men today to those of the bottom 30 percent in the past will show a worse trend than comparing the bottom 10 percent (or 30 percent) in both years.

Like other advocates of the marriageable men hypothesis, Kearney also points to the fact that men’s labor force participation—the share who are working or looking for work—has fallen. However, that trend dates to the 1940s, and little of it—according to men’s own survey responses—reflects difficulty finding work. As I have shown in other research, by an absolute economic “marriageability” threshold, men are at least as marriageable now as they were in 1979. At the same time, if “marriageable” means that a prospective husband earns some multiple of what a woman earns, then men’s marriageability has indeed declined. But that is because women have made such remarkable advances.

The distinction between an absolute marriageability threshold and a relative threshold is important for policy. Throughout The Two-Parent Privilege, Kearney asserts that men are having a terrible time in the modern economy, with statements like, “It has become increasingly difficult, for example, for someone without a high level of education or skill to achieve economic security and success in the U.S.” Correspondingly, many of her proposals are aimed at boosting men’s economic outcomes. For instance, she wants to expand the Earned Income Tax Credit (an earnings subsidy for low-income workers), reduce incarceration, and step-up prisoner reentry efforts.

But is the decline in marriageability related to economic deterioration or rising affluence? If, in real terms, men are doing better than ever and only losing ground relative to the even more impressive gains made by women, the problem may be that both men and women are setting the economic bar for men’s marriageability too high. Or perhaps women’s economic gains allow them not to settle for men whose non-economic marriageability leaves a lot to be desired. To put a finer point on it, if declining marriageability is about economic deterioration, that has different implications for policy than if it is about rising affluence.

Cultural Contributions

Turning to other explanations for family decline, Kearney does believe culture is important. She presents evidence from her clever 2015 study with Phillip B. Levine showing that exposure to the MTV show 16 and Pregnant lowered teen pregnancy rates. If pop culture can reduce single parenthood, it may have been an important part of its long-run increase in the wake of the countercultural 1960s.

Kearney also cites her 2018 research with Riley Wilson on the fracking boom, which may have provided an “as good as random” boost to men’s pay in the affected geographic areas. She found that even though men’s earnings rose in these areas, rather than stimulating marriage it seems only to have increased the number of births (including those out of wedlock). Kearney contrasts this result with the effects of the Appalachian coal boom of the 1970s and 1980s, which did increase marriage. To square the two results, she speculates that the culture changed. In earlier decades, the stigma around nonmarital childbearing was stronger than it is today, so economic gains led to more marriage. Today, given changed norms around single parenthood, economic gains are insufficient to increase family stability.

Other research focusing on cultural change dates the shift in norms closer to the 1960s. Economists George A. Akerlof, Janet L. Yellen, and Michael L. Katz argue that the availability of legal abortion and the birth control pill increased pressures on women to engage in nonmarital sex and reduced pressures on men to marry women if a pregnancy resulted. Consistent with this hypothesis, Rachel Sheffield and I have documented a sharp decline in post-conception, pre-birth marriage (“shotgun marriage”). In the early 1960s, over 40 percent of births resulting from nonmarital pregnancies were preceded by a wedding. By the late 2000s, that figure had fallen to about 10 percent.

That cultural change is an important factor in the deterioration of the family is also suggested by the many parallel declines in “associational life” that have occurred over the past 50 years. Not just family life, but community, religious, civic, and institutional life have become less vibrant. Kearney’s solutions to rising family instability also target culture. She advocates “fostering a norm of two-parent homes for children,” though she doesn’t have any specific proposals for doing so beyond citing “organic” shifts in media messaging.

Policy’s Role

Finally, other researchers—most prominently, but hardly exclusively, Charles Murray—have argued that the incentives in federal safety-net programs have contributed to the increase in single parenthood. By reducing benefits when income rises, many safety-net programs discourage couples from marrying. The very existence of generous—if far from lavish—benefits also makes single parenthood more viable.

Kearney is not having it. She says it is a “mistaken assumption” that government assistance affects family structure and asserts that it is “simply untrue and unfounded” that welfare benefits have played a significant role in the rise of single parenthood.

But her cursory review of the research is far too one-sided, in my view. In one revealing passage, Kearney declares, based on her 2004 study, that family caps—a state option to limit welfare payments when beneficiaries have additional children—don’t reduce nonmarital fertility. She says as a result of states implementing family caps, the lives of single mothers “were made more difficult by a public policy that was rooted in bad assumptions.” But more than a decade after her paper was published, a comprehensive review of welfare reform studies (including Kearney’s) reported mixed evidence on the question, with two of six papers finding that family caps did reduce nonmarital fertility, two finding they did not, and two yielding ambiguous results.

Moreover, three trends suggest that welfare reform may have increased family stability. First, among the most disadvantaged children, the share of children living with married parents stopped declining 30 years ago. From the late 1960s to the early 1990s, living with married parents became rarer among children with the least-educated and poorest mothers. But then it bottomed out. Around the same time, the nonmarital birth rate, which had been rising since at least 1940, leveled off. It eventually began to drop and in 2021 was lower than at any time since 1987. Finally, the teen birth rate (and nonmarital teen birth rate) also began steady declines at around the same time.

As it happens, the early 1990s was a period of state experimentation with welfare reforms, political pressures to reform the system (“end welfare as we know it”), and federal activity to pass legislation that would do so. It culminated in the landmark Personal Responsibility and Work Opportunity Reconciliation Act of 1996, which overhauled the nation’s welfare system. Notably, employment of single mothers, especially the least skilled, rose sharply beginning in the early 1990s and remained elevated thereafter. Meanwhile, child poverty fell to an all-time low—a result that is not exclusively the result of welfare reform but for which the reform appears central given how much of the drop was due to pre-tax and transfer income. This evidence is far from rock-solid in demonstrating the causal impact of safety-net policies on family stability, but it adds up to a much stronger case than Kearney admits.

Since Kearney rejects the notion that transferring money to people does harm, she advocates a much bigger safety net for all families with children, including a universal child allowance and universal pre-K. These kinds of policies are not really a solution to the problem of rising single parenthood. They effectively amount to a concession to Kearney’s critics, who argue that single parenthood itself isn’t the problem. Rather, it’s the economic cost of single parenthood, and policymakers could choose to support these families enough that it wouldn’t matter. Furthermore, somewhat undermining her case, Kearney notes that research by Nobel laureate James Heckman has found that Denmark’s more expansive welfare state does not appear to translate into higher intergenerational mobility.

More Than Money

At the end of the day, Kearney attaches too much importance to having enough money. As noted, she emphasizes wage stagnation and income inequality as causes of family breakdown. She also focuses on insufficient family income as a mediator of single parenthood’s harms. For example, noting that single motherhood appears to have a stronger negative impact on boys, Kearney might have probed the importance of same-sex role modeling. Instead, she sticks to her framework in which money affects what families can afford, how stressed they are, and the spare time they have to give children, positing that boys may be extra sensitive to these diminished inputs. Finally, Kearney’s solutions focus heavily on providing more money to families or helping men earn more money so that they will be more marriageable.

If only money mattered, addressing single parenthood would be much easier, since we have policy levers for transferring money and increasing the ability of men to earn more. Unfortunately, transferring money may itself be a big part of the problem. And the cultural factors at play resist policy intervention.

Kearney’s proposals for education are not especially well aimed at reducing single parenthood. She wants “improvements” to primary and secondary education, a “massive” increase in federal spending on postsecondary schools, and more apprenticeships and career and technical education programs. But marriage has eroded even more for moderately educated parents than for the least-educated parents, and today, the rates of the two groups are nearly indistinguishable. It is unclear that raising educational attainment will have much of an impact. The higher marriage rate for college-educated parents surely reflects factors other than their having earned a paper certificate.

However, there may be one way for schools to support the sort of cultural change that could make a meaningful difference. They could adopt curriculums that emphasize the “success sequence,” as does the Vertex Partnership Academies network of charter schools founded by my American Enterprise Institute colleague, Ian Rowe. The success sequence involves putting high school graduation, work, and marriage before childbearing; poverty rates among adults who took such a path are vanishingly low. We could use more causal research to establish the impact of following the sequence, but experiments to encourage kids to forge a successful path seem warranted. Such curricular experimentation seems hard to imagine within public schools for the time being, which points toward expanding the number of charter schools and providing more vehicles for school choice, such as education savings accounts.

Despite my not sharing Kearney’s perspective on the causes of the rise in single parenthood and preferring different policy measures to reverse it, I wholeheartedly agree with her as to its fundamental importance. Advocates for children and for greater social mobility should be grateful for her informative, nuanced, and humane case that single parenthood is one of the greatest barriers we face to expanding opportunity. Policymakers and analysts across the ideological spectrum should consider it one of the defining challenges of our time.

Scott Winship is a senior fellow and the director of the Center on Opportunity and Social Mobility at the American Enterprise Institute.

This article appeared in the Winter 2024 issue of Education Next. Suggested citation format:

Winship, S. (2024). It Takes Two: Does The Two-Parent Privilege get it right? Education Next, 24(1), 70-75.

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