Jonathan Zimmerman teaches history and education at New York University.

On Sept. 5, 1994, 20,000 delegates from 179 countries gathered in Cairo for the International Conference on Population and Development. Unlike prior population meetings, which focused mainly on family planning services, the Cairo convention endorsed equal access to education for girls. It also demanded “reproductive rights” — including rights to contraception and information about sex — for adolescents of both genders.

Two decades later, girls’ education has expanded steadily around the globe. But sex education has stalled. In most countries, children and adolescents receive a smattering of information about their reproductive organs and a set of stern warnings against putting them to use. Whereas the Cairo meeting envisioned preparing youths to be autonomous sexual beings, most contemporary sex education simply admonishes them against sex itself.

And that’s not because certain parts of the world are “conservative” or “traditional” on the topic. Instead, conservatives around the globe have united across borders to block or inhibit sex education. On issues of sex and reproduction, it’s not East vs. West anymore. It’s liberals vs. conservatives, each of which often have more in common with their ideological soulmates in other parts of the world than they do with people next door.

This configuration was already apparent at the Cairo meeting, where delegates from seven countries — including the host nation, Egypt — dissented from the resolution on sex education. As an Iranian representative explained, the resolution “could be interpreted as applying to sexual relations outside the framework of marriage, which is totally unacceptable.”

The resolution was also condemned by the Vatican, which had sent a papal envoy to Tehran earlier that year to coordinate its campaigns against the Cairo accords. The resolution caught the attention of growing Muslim immigrant communities in Europe, who joined hands with native white conservatives against sex education. On most issues, including immigration itself, these groups were at loggerheads. But on sex education, they saw eye to eye.

Meanwhile, a burgeoning network of international organizations bound conservatives together. Born a year after Cairo, the World Congress of Families united Christians, Muslims, Hindus and Jews who opposed abortion, same-sex marriage and sex education. It received a letter of praise in 2004 from President George W. Bush, who had declared that one-third of U.S. foreign assistance for HIV/AIDS prevention would be devoted to abstinence-only education.

But the global right was not simply a product of conservative U.S. support, as liberal critics too often assume. When U.S. delegates condemned a reference to “reproductive health services and education” at a U.N. special session on children in 2002, the other opponents of the language were Iran, Iraq, Sudan, Libya and Syria. On sex education, one observer wryly noted, the United States had united with the “axis of evil” that it otherwise reviled.

With the election of Barack Obama, U.S. foreign policy became friendlier to sex education and reproductive rights. But the global campaign against sexual information for adolescents continued. In Asia and Africa, especially, critics railed against “Western” sex education. They simultaneously made common cause with their conservative brethren in the West, borrowing the rhetoric of family values and — increasingly — multiculturalism.

Consider the reaction to the U.N. Educational, Scientific and Cultural Organization’s 2009 “International Guidelines on Sexuality Education,” which urged schools to address often-ignored topics — including masturbation, abortion and contraception — so that adolescents could develop their own sexual selves. One critic in Singapore blasted the “U.S.-centrism” of the guidelines, which were authored by two American educators. He was echoed by a right-wing opponent in the United States, who decried the standards as a “one-size-fits-all approach” that was “damaging to cultures, religions, and to children.”

In the 20 years since Cairo, the world has globalized as never before. Hundreds of millions of people have migrated among countries, while digital technologies forge new connections across them. But as the fate of sex education shows, globalization does not necessarily mean liberalization. It can also bind formerly isolated conservatives into powerful new coalitions, which can lead to stalemates on causes that liberals hold dear.

To be sure, some Western European countries still provide sustained attention to adolescent sexuality in their schools. But they have also come under fire from growing Asian and African immigrant communities, which are repulsed by schools’ rhetoric of sexual autonomy and choice. Emphasizing “modesty and obligatory innocence,” as one Dutch observer wrote, these newcomers do not see sex outside marriage as a “choice.” It’s a sin, instead, and it’s scandalous for schools to suggest otherwise.

“How can a sexuality, reproduction and health perspective based on individual rights become a global norm?” a Swedish educator wondered in 2004, on the tenth anniversary of the Cairo conference. Ten years after that, we’re no closer to a global norm on sex education. We might even be further from it.

Read more on this issue:

Ruth Marcus: Sexism in the Senate