Three Parent Privilege?

Why “two” isn’t arbitrary—and why “three” isn't better

I (Josh) just finished Melissa Kearney’s The Two-Parent Privilege (book link), and I felt compelled to write. On the one hand, I’m genuinely glad to see her admission that two-parent homes are advantageous for children. On the other hand, she keeps stopping short of the obvious truth about why.

Kearney deserves credit for naming what she calls the elephant in the room: children generally do better when raised by two married parents. In a moment when even modest acknowledgments about family structure draw fire, saying so is a public service—and I applaud her for that. She writes

“Marriage is the most reliable institution for delivering a high level of resources and long-term stability to children. There is simply not currently a robust, widespread alternative to marriage in US society. Cohabitation, in theory, could deliver similar resources as marriage, but the data show that in the US, these partnerships are not, on average, as stable as marriages.” (p. 15)

That admission is exactly where the falter shows. She concedes that marriage is the most reliable arrangement for stability and resources, but stops short of naming why it truly outperforms: because the two parents, historically, were united in “marriage,” a lifelong, monogamous, and sexually complementary relationship that also brings biological connection. Stability and resources are part of it, but so are sex-specific parents and biological ties—features that change how adults love, protect, and invest in their child. Without that definition, her case drifts back to a purely economic frame: two adults can give more time, energy, attention, and opportunity.

Why Not Three?

On her terms, the logic leads somewhere she doesn’t want to go. If households are investment engines and children are mainly assets with potential to invest in, then—sarcastic but serious question—why stop at two? Why not a three-parent privilege? Or a four-parent privilege for double the privilege of before? If it’s just about maximizing inputs, more is better. But we all instinctively know that isn’t right. The number two wasn’t plucked from the sky; it’s been optimal because it counts the two types of people who have always been required for the process of human creation and are still required today. That’s not a glitch; it is a good design. And it is as old as humanity: a mother and a father, the two people who can create the child, joined by biological connection and sexual difference. From the start, it forges a peculiar bond: the child often looks like the people who made them, carries their story, and calls forth their better angels. Those realities don’t just add hours to a household ledger; they change the love and responsibility on offer. Children reliably move their mothers and fathers to invest, secure, protect, and nurture them—and they do so at a level no substitute arrangement consistently matches. That’s why, across time and cultures, this has been the safest and most stable setting for children to flourish. To reduce that mystery, how we bond, attach, invest, sacrifice, or even die for our kids, to a stack of economic inputs feels wrong on its face, and the research keeps saying as much.

Kearney’s own evidence keeps pointing in this direction:
“For example, there is a study using large-scale, nationally representative data showing that stepmothers generally do not invest as much in their stepchildren’s health as do biological mothers, even after adjusting for household income and other relevant characteristics. Another large-scale study finds that adolescents who experienced their mother marrying a stepfather after parental divorce had worse behavioral outcomes and more negative feelings than adolescents whose biological parents remained continuously married.” (pp. 66–67)

What she’s pointing to is the phenomenon Daly and Wilson labeled the Cinderella effect: that stepparents, on average, invest less in non-biological children, and the risk profile for children changes accordingly. In their cross-national analyses, the per-capita risk of fatal battering for very young stepchildren was on the order of one hundred times higher than for children living with their genetic fathers. That doesn’t brand stepfathers as bad; many are devoted and sacrificial, but it does signal that there is, on average, something uniquely protective about biological ties. In other words, inputs aren’t fungible. Biology and sexual difference help explain why two biological parents confer advantages that can’t be replicated by simply adding more adult “time and money.” It’s the piece that should have been named in her book.

Fathers Matter (sort of)

She also emphasizes the plight of boys and the importance of fathers. The research she cites shows that the more dads in homes in the neighborhood, the better the outcomes. And not just for individual families but across the community, an effect especially strong for Black boys. Read plainly, this isn’t a case for “any second adult”; it’s evidence that sex-specific parenting matters. A mother’s care, even doubled, is not the same as an involved father’s presence. Little boys need their dads.

And yet when the implications sharpen, Kearney retreats to the familiar “no difference” claims about same-sex parenting, leaning on the American Sociological Association’s 2013 amicus brief that reported no differences in outcomes for kids raised in same sex households once controls are added.
Methodologically, these claims rest on shaky ground: recruiting from small populations, under-powered samples, strong selection effects, short follow-up windows, and heavy reliance on parent-reported outcomes (how well parents say their own kids are doing), which are vulnerable to social-desirability and confirmation bias. For point-by-point critiques, see The parenting study that should have ended the debate and Schooling AI about the same-sex parenting literature.

But even setting methods aside, this “no difference” move breaks the thread of her own evidence. Earlier, she emphasizes two things:

(1) non-biologically related parents do not invest in—or protect—children at the same rates (the Cinderella effect, e.g., stepmothers spending less on stepchildren’s health and step-family transitions worsening behavior), and

(2) the presence of fathers—in the home and even at the neighborhood level—improves outcomes, especially for boys.

If both of those are true, it cannot also be “no different” to remove a mother or a father and/or replace a biological tie with a non-biological one in order to create a same-sex parenting arrangement. The very mechanisms she highlights—biological relatedness and sex-specific parental contributions—are precisely what “two parents” of the same sex must forgo. That’s not a trivial distinction to be controlled away; it’s part of the core of why two biological parents outperform every other arrangement.

Affirming that mothers and fathers matter isn’t bigotry; it’s biology. We need the courage to follow the evidence where it leads and not be intimidated by the media, the lobbies, or the special interests when the data (and common sense) all point in the same direction.

Here is the non-negotiable: children are not optimization problems; they are persons with prior claims. Rights precede resources. Even if some alternative arrangement could, on paper, marshal more money or hours, we do not purchase marginal inputs by severing a child from his or her own mother or father. The child’s claims come first. A child has a rightful claim to be raised by his or her own mother and father; adult preferences and novel arrangements must be measured against that claim, not the other way around. Organizing marriage around the child’s rights (rather than adult desires) clarifies why “two” is both necessary and sufficient: it links the child to the two people who created them, integrating identity, love, and responsibility in one home.

So yes—credit to Kearney for naming the elephant in the room and for her admission that two-parent homes matter. But a complete account requires naming why. The case for two parents is ultimately a case for the institution of marriage. It upholds the natural family: a man and a woman united in a lifelong, monogamous, sexually complementary union, which also safeguards the children born to them by binding the whole family together. That is the frame that makes sense of the data, explains why two beats three, and avoids the contradictions that appear when we reduce family to economic units.

The invitation is simple: be fully courageous. Say the whole thing. Children flourish when raised by their mother and their father. If we want more flourishing, we have to say that truth plainly and design policy, culture, and law around it.

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About Them Before Us:

Them Before Us is a global movement committed to defending children’s right to their mother and father. We believe that adult desires should never come at the expense of a child’s fundamental needs.

We are not professional lobbyists or political insiders. We are ordinary people with an extraordinary conviction: children must come first in every conversation about marriage, family, and fertility.

We exist to make one thing clear: when adults sacrifice for children, society thrives. When children are forced to sacrifice for adults, everyone pays the price.

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