These days, residents of different countries often drink the same coffee, buy clothes from the same retailers and use the same social media apps. Globalization has erased many traditional differences around the world. But when it comes to parenting, habits still vary from country to country to a startling degree.

In many American circles, “helicopter parents” monitor their children’s every move, and outliers who let their kids walk home from the playground on their own risk rebuke by local police. Meanwhile, in Switzerland, even kindergartners walk to school without adult supervision. And Sweden and Germany offer popular “forest kindergartens,” where children stay outdoors in nearly all weather, playing and exploring with minimal adult guidance. In those countries, unlike in U.S. classrooms, early literacy and numeracy are not part of the curriculum, even in regular preschools; teachers emphasize play and crafts instead. In China, by contrast, strict parenting is a much-discussed part of national life — and was the subject of a hugely popular television series, “Tiger Mom.”

Discussions of differences like these often focus on culture. China’s Confucian tradition, for instance, emphasizes respect for elders, which some observers suggest could be one influence on authoritarian parenting. But we have found in our research that varying parenting styles among nations are rooted primarily in economics — specifically, economic inequality. The common denominator in countries where intense, achievement-oriented parenting abounds is a large gap between the rich and the poor. Conversely, where inequality is low and governments provide safety nets, a more relaxed, permissive parenting style holds sway.

That suggests that to reduce the epidemic of hypercompetitive and overinvolved parenting in the United States, simply exhorting people to be more laid back won’t work. The only solution is to attack the problem at the root: by combating inequality.

We have experienced some of the differences in parenting cultures firsthand. Matthias Doepke is raising his three boys in Evanston, Ill. There, as in other upper-middle-class enclaves in the United States, it is common to sign up 3-year-olds for classical-music lessons following the Suzuki method, which requires parents to attend all classes and practice frequently with the kids. When his youngest was choosing an instrument, a teacher recommended the viola, on the utilitarian grounds that it’s easier to get a viola scholarship to college than a violin scholarship —which people found amazing. It was a different story for Fabrizio Zilibotti, who raised his daughter in Sweden for her first few years. When he signed her up for piano lessons with a demanding Eastern European teacher at age 5, many of his Swedish friends frowned, arguing that kids should not be pushed too hard. (The Dutch, for their part, have a saying that captures the idea that parenting shouldn’t be about creating super-achievers: “Just be normal. That’s already crazy enough.”)

One way to analyze cross-cultural parenting differences like these would be to look at the time that parents spend directly helping their children with various tasks. American parents now spend two hours per week helping kids with their homework; Dutch parents less than half as much. But differences in survey methodology across countries make such comparisons difficult.

Instead, for our investigation, we used beliefs about the values that should be instilled in children as a proxy for parenting styles. That’s because strict or laid-back practices flow from ideas about the purposes of parenting. The World Values Survey, which periodically queries thousands of respondents in almost 100 countries about their attitudes on a wide range of matters, includes a question asking parents to select up to five values, from a list of 10, that they regard as most important for rearing children. We placed nations on an intensive-permissive parenting continuum based on their relative rankings of “hard work,” “obedience,” “imagination” and “independence.”

In the United States, about two-thirds of parents include hard work on the list of top values to instill in children; in Sweden, only about 11 percent of parents place hard work that high. This lines up with differences in economic inequality: In the United States, households in the top 20 percent of the income distribution earn on average almost nine times more than households in the bottom 20 percent. In Sweden, the top quintile earns 4.3 times more than the bottom.

China is perhaps the epitome of the high-inequality, high-intensity-parenting nation. Partly confirming the stereotype of the “tiger mom” — a term often applied to Asian American mothers but widely used in China, too — 90 percent of Chinese parents, even more than in the United States, place hard work among the most important values to pass along to children. Our research suggests that’s because economic inequality is higher still in China than in the United States: The income ratio between the top and bottom fifth of households exceeds 9.5.

Japan serves as an interesting test for our thesis, since it shares some cultural characteristics with China (both countries are influenced by Buddhist and Confucian traditions), yet it’s more economically egalitarian. In Japan, the economic inequality ratio is higher than in Sweden but lower than in China and the United States. Indeed, Japan’s parenting attitudes, as reflected in the World Values Survey, are closer to those in culturally remote Germany and the Netherlands than to China’s.

Across all postindustrial economies, in fact, we found that the share of parents emphasizing “hard work” lines up remarkably consistently with the degree of economic inequality.

It’s easy to see why. If inequality is low and schools in different areas of the country are roughly the same caliber (these two things often go hand in hand, though not always), children’s grades won’t do much to shape their future material comfort; the kids will enjoy a similar standard of living whether or not they achieve high marks. Parents are more likely to conclude that happiness lies in finding a career suited to one’s personality and interests, and encourage creative exploration toward discovering that niche.

But if inequality is high, parents will perceive that their children must outpace their peers to be comfortable in the future. The importance of achievement rises.

Many parents probably find something to like in both approaches to parenting, the hard-driving and the permissive. But the data suggests that people believe they must pick one or the other: Countries that embrace “imagination” as a goal downgrade “hard work,” and vice versa.

Admittedly, the correlation we’re describing doesn’t prove that economic differences shape parenting styles. It could be, for instance, that cultural aspects drive both parenting and the design of policies and institutions that determine inequality. But the economic explanation looks more persuasive when you see that the relationship between inequality and parenting also holds within countries over time, not just among countries.

Many people who grew up in America in the 1970s remember a low-pressure childhood with a lot more freedom and independence than today’s kids enjoy. Data backs up those impressions. In 1969, 41 percent of American children biked or walked to school, a figure that had dropped to about 18 percent by 2014. In 2017, according to the American Time Use Survey, a typical American parent spent close to twice as much time each week interacting with their children as parents did in the late 1970s (almost 28 hours for both parents in 2017, up from 14 hours in 1976). And education-oriented activities grew the fastest.

These changes put a significant burden on parents. The numbers are even more striking when you consider that, in 1976, mothers were far less likely to be in the workforce than in 2017, which means that parents today are working more and doing more hands-on parenting.

Those changes track trends in inequality: In the United States, a household with two college-educated earners in the late 1970s made about $30,000 more (adjusted for inflation) each year than a household with two high-school-educated earners. By 2010, the gap had become a chasm: nearly $60,000 a year.

In most advanced economies, both inequality and the intensity of parenting have been on the rise since the 1980s. And the popularity of intensive parenting has grown the most in countries where inequality has increased the fastest. The exceptions are intriguing, too: Income inequality has declined in Turkey and Spain — and in both countries, the percentage of parents endorsing “hard work” as a crucial value for children has gone down.

When parenting becomes an arms race, the rich have a clear advantage — another problem in countries that embrace the intensive style. Obviously, when you’re holding down two or three jobs, you have less time to drill your kids on math, and you may not have access to tutors, test prep and private coaches. It’s a vicious circle: Inequality leads to the rise of competitive parenting, which further exacerbates inequality for the next generation. We’re seeing that play out in the United States.

You might think that, above a certain income level, there would be diminishing returns for competitive parenting. Once you have an excellent school (probably in an expensive neighborhood), SAT tutors, music lessons and select sports leagues, aren’t the boxes of intensive parenting checked off? But American inequality has been particularly pronounced at the top, with larger and larger shares of income going to the top 1 or even 0.1 percent of earners, so even parents near the peak of the income scale feel inequality’s pressures. The desire to push children one rung higher is relentless. Indeed, since the 1980s, couples with more money and more education have increased the time and money spent on their children at a much faster rate than others.

Many Americans lament the rise of the hovering, overinvolved parent and the loss of unscheduled free time for young people, but our analysis suggests that simply preaching the virtues of less-frantic child-rearing practices in faraway places will not do much to ease pressure on parents here. We should instead address the causes: We ought to create policies and institutions that push back against rising inequality by offering children paths to success that aren’t overly shaped by grades and class rank.

We can look abroad for examples of such measures. They range from free day care, to more equal funding of primary and secondary schools, to investments in vocational training and apprenticeship programs. With the right institutions in place, parenting culture will adjust. Change the economic incentives, and the helicopter parent phenomenon will fade away.