If polyamory is on the rise, there may be good economic reasons. But economist says arrangements are 'tricky'

Social attitudes toward dating may be a factor driving interest in polyamory, but economic forces could also be playing a role, says Mindy Marks, associate professor of economics at Northeastern University.

Recent news coverage of polyamory has shined a light on non-traditional relationships, such as "throuples." While the practice still seems relatively marginal in the U.S., interest in polyamory (meaning multiple romantic relationships or sexual partners) appears to be on the rise—particularly among Gen Z.

Reporting on the subject suggests that, as marriage rates continue to decline and the cost of living goes up, more and more people approve of non-traditional family arrangements, such as open marriages, to find companionship, pursue their careers and stay afloat financially.

There's no question that family structures have changed in recent decades, moving away from the traditional nuclear family (two parents and their dependent children) to encompass a more diverse set of relationships and living arrangements, Marks says. Look across the millennia, and it's no different, she says.

Whatever the primary drivers are, Marks sees polyamory as having some economic basis. Northeastern Global News asked her to weigh in on the recent wave of headlines about polyamory, and on the status of the nuclear family in 2024.

Her comments have been edited for brevity and clarity.

As an economist, what do you think about the discourse surrounding the rise of polyamory? Does it confirm that we've moved beyond the nuclear family into new social and relational territory?

Marriage, partnerships and coupledom—however you want to put it—have responded to economic forces for as long as they've been institutions. Think about marriages that were intended to be political alliances to stop warring factions, or in developing countries when people would marry to ensure adjoining property rights of land in order to grow farms at scale.

If I were to speculate, I could give you two economic reasons why you might see a rise in polyamory. One has to do with imbalanced sex ratios in communities, especially in more highly educated communities, where there are more college-educated women than college-educated men.

Assuming that people don't want to change their preferences to partner with somebody with a similar education level, then some unmatched women might be more open to considering the sort of partnership arrangements that don't look like the traditional nuclear family—because there literally just aren't enough men.

If we imagine that men might have preferences wherein they would prefer a polyamorist relationship to a traditional relationship—again, thinking about this in terms of these "econ" models of whichever gender is in shortage has a little more power—then they can steer relationship outcomes toward their preferences.

The second possible reason—and again I'm just speculating here—might have to do with child-rearing. The nuclear family in some sense has changed in that it traditionally had one bread-winner and one stay-at-home parent. And that's just not the modal marriage you see nowadays.

Today, the modal married couple has two working parents, and that's in part because of a variety of economic pressures. There is a greater need for a second bread-winner when it comes to paying for housing and good school districts and vacations and all of the necessities and luxuries of modern life. But then, because both parents are working, there's less time for what economists refer to as "household production," or all of the unpaid labor.

It's things like child-rearing, cooking, vacation planning, cleaning the bathroom. It's all these things that need to be done in order to have a functional household—but that takes time, right? So in that sense, there are advantages to having, for example, three people in the household as opposed to just two, because you could have the income of a dual-income family and an entire other person's worth of time devoted to child-rearing, or just working out the kinks of everyday life.

We've known for some years that birth rates—not just here in the US, but throughout the world—have been on the decline. How does that factor into this shift away from the nuclear family?

I think that's clearly a piece of it, too. Kids are expensive, and they're expensive both in terms of monetary cost, but also in terms of time cost. Both of these economic forces lead to declining birth rates. Also, female time has become better rewarded than it used to be. In that sense, we call this the opportunity cost. The cost of having kids is a time cost. If I have to take two years off of work to be at home with my kid, that would mean forgoing two years of my earnings—and that's more money than it would have been in the past, and more beneficial to our family than it might have been.

But there's also some evidence that some of the direct costs of child-rearing, like childcare costs, have been rising at rates faster than inflation—they might literally price some people out of having children in the first place. The empirical research on this is a little fuzzier because there are declining birth rates in many societies, so governments have been trying to move these levers to nudge the birth rate up—and they've managed to do so a little. Economics plays a role, but part of it is social norms. Society adapts to a different style of family than it had before.

How much of the conversation is about economic incentives, and how much is it about shifting social norms?

Marital structures is one of these areas where public opinion has changed at an incredibly rapid rate. It took not even a generation for a majority of people to switch from disproving of gay marriage to accepting it as a good institution. Opinions about interracial marriage change, on the other hand, changed much more slowly.

I think that once you start with alternative family arrangements, it's easier to accept different kinds. Then the institutions in society become more welcoming to them, and then children don't feel stigmatized if the "right" set of parents don't show up at the parent-teacher conference. I do think social change has played a role; but none of this is really new either.

Think about the free love and communes of the '60s and '70s, etc. These institutions have been around before. Part of this conversation has to do with economic incentives. We have public policies that support or discourage certain kinds of familial relationships. You can qualify for some benefits if you're married, you might lose your health insurance if you marry because your income exceeds the income thresholds, and so on. And I don't think these policies are intentionally trying to promote or discourage marriage, but they do so in practice.

Do you see polyamorous and other non-traditional relationships and family structures flourishing in the future? If so, how might that impact birth rates?

I would be shocked if we saw an increase in birth rates over the next 10 years. They may stabilize; they may continue to decrease. Women are going to continue to want to make money and want some autonomy. Barring some major technological advancement, I don't see a change. Like I said, lots of governments have been trying to push up the birth rates and they've hardly moved the needle. That one I am willing to believe will continue.

On polyamory, you know, I'm a little long-term suspicious. It's hard enough to solve problems to keep two people together. There are all of these little internal negotiations that have to happen for some couples to function. With two people, eventually you play a repeated game and you can reach some sort of equilibrium. There are a whole bunch of econ models that show that the more the participants, the harder the decision-making gets. Three just feels a lot tricker than two in terms of working out all of the stuff that needs to get worked out.

This story is republished courtesy of Northeastern Global News news.northeastern.edu.