Online dating is often treated as a wacky new trend. But it’s one of the biggest social transformations in human history.

Since people started living in big societies several thousand years ago, couples have gotten together mostly because their families wanted them to. The idea that it is normal and OK for people to find and choose their spouses “on their own” is a fairly new thing, only a few hundred years old at most. Even since then, this individual search for love has usually ended with a romantic introduction through family or friends.

Greater numbers of diverse couples in turn change the demographics of their communities, their workplaces, their religious groups, their children’s schools and so on.

While these matches certainly aren’t the arranged marriages of old, they’re not all that different in outcomes: people marrying other people who have been vetted and approved of by their close confidants, and who are typically from similar family backgrounds in terms of race, ethnicity, social class and religion.

But suddenly, in a blink of history’s eye, the U.S. has become a place where it is common for newlyweds to have recently been perfect strangers — without any friends or acquaintances in common, without families that knew each other — until the couple found each other through online dating. While couples who met through the internet were fairly rare in the 1990s, they’ve increased exponentially since the turn of the century, and now finding love online is the most common way that romantic relationships begin in the U.S., accounting for a third of new couples and marriages.

This rise in the pairing off of total strangers is changing the kinds of couples that become families, and that is changing the makeup of the next generation of Americans they raise. Most dramatically, online dating is acting as a desegregating force in the U.S. and creating families that blur social boundaries, which can lead to those boundaries becoming less meaningful over time.

In my research, I’ve found that present-day partners who first connected online are more likely to be interracial and of different ethnicities than those who met other ways (30 percent versus 23 percent). They are also more likely to be from different religions (51 percent versus 38 percent), both in how they were raised and in which religion they practice as adults. Couples who met online are also more likely to have one college graduate and one nongraduate (30 percent versus 22 percent), bridging the biggest educational and social class divide in America today. And it isn’t just the weakest racial boundaries than get crossed more online: Black-white couples, perhaps the most heavily discouraged type of couple diversity in American history, are more likely to occur from online dating than offline (8 percent versus 3 percent).

The research used probability samples of American adult couples from 2009 and 2017, using a survey completed online but including those who did not have prior internet access to ensure accurate representation across the country.

It isn’t clear from this research if these effects are changing as internet dating evolves and grows, but as the numbers of people who find love online continues to climb, the impact of the phenomenon on the diversity of the U.S. population of couples as a whole is increasing. Greater numbers of diverse couples in turn change the demographics of their communities, their workplaces, their religious groups, their children’s schools and so on.

Diverse couples have enormous potential to bridge the social groups that define their diversity, acting as pathways for information, introductions and social support across the different kinds of families and communities they were raised in. Diverse families can be powerful agents of desegregation, creating diverse social networks of friendships and acquaintances around them.

It didn’t have to happen this way. Online dating could have developed as merely a more efficient system of friends and family setting up singles with other singles they know. Such a system could still become the standard way to find love online in the not-too-distant future, such as through social networking sites, and this would probably not create more diverse couples than traditional romantic sources.

One can also imagine people using online dating tools to find mates who are as similar to themselves as possible. People attempt to do that to some extent right now: Every study of how online daters behave on these sites has found that they are more likely to message and respond to other people of the same race or ethnicity, the same religion, the same education level, etc. But people are also biased in whom they choose to interact with offline. Since the dating pools on most sites and apps are so much more diverse than offline pools, it only takes a little open-mindedness online to produce more diverse couples.

Still, online dating could be used to find a partner who matches not just in one way, but in just about every way. It may be hard to find another Swedish Lutheran libertarian punk rock fan who loves rock climbing and has an MBA at your workplace or local tavern, but you can find them when looking at all of the online daters in your city, state or country. While this kind of pickiness online seems to be rare, there’s no reason it couldn’t become normal. In that case, online dating could become even more segregating than other sources of romance.

There are also ways in which online dating hasn’t really changed anything. The internet is not creating more heterosexual couples than would exist otherwise, though it may be increasing the number of same-sex couples. Since at least the mid 1990s, the rate of U.S. residents in their 30s and 40s who are cohabitating or married (72-73 percent), and of women aged 30-44 who have a boyfriend or husband (87-89 percent), has been steady. There seems to be some growth in the numbers of same-sex couples since the 1990s, but it is hard to disentangle the effect of the internet from the profound social and legal changes that have also occurred for same-sex couples during this time.

Despite its marketing, I have not yet seen clear evidence that couples who meet online are happier or stay together longer. And the tendency for people to find romance with those who agree with them politically (54 percent of couples are party-homogenous) is roughly the same online and off. But these could change in the future as well.

The industry has so far largely avoided deep public scrutiny, particularly compared to the recent spotlight that has been aimed at other tech companies.

Online dating may soon account for the majority of new couples in the U.S., the majority of new marriages and the majority of new parents. Yet in spite of this important social role, the industry has so far largely avoided deep public scrutiny, particularly compared to the recent spotlight that has been aimed at other tech companies. There is a growing conversation about the ways the matching algorithms in dating sites control who sees whom, however, which may be discouraging even more diverse pairings.

Expect more public attention to how the most popular sites and apps operate, how their algorithms and interfaces sort users, and what data they keep, share and sell. Expect “panics” about online dating, particularly from parts of society that stand to lose if their young people marry outside their group. And as the stakes of this social change become clearer to everyone, expect online dating to become more politically contentious even as it becomes a more taken-for-granted part of social life.