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Stephanie Coontz is the director of research at the Council on Contemporary Families and author of “The Way We Never Were: American Families and the Nostalgia Trap.”

Older generations always seem to fret about the sexual behavior and romantic lives of the younger crowd. In the 1920s, there was alarm when boys stopped visiting in the parlor and started driving girls around in what one newspaper called “a house of prostitution on wheels.” This worry paled in comparison to the panic evoked by the rowdy sexual revolution that began in the late 1960s.

In the 1980s, observers were rightly alarmed by the growing prevalence of early teen sex, AIDS and sexually transmitted diseases. In the first two decades of this century, anxiety shifted to the college hookup scene and the emergence of dating apps to facilitate casual sex.

Here’s a look at some surprising takeaways from recent research about the sex lives of the millennial generation. (Claritza Jimenez/The Washington Post)

Recently, however, a new concern has surfaced, with the finding that young adults, those age 20 to 24, are now having less sex than Gen-Xers or baby boomers born in the 1960s did at the same age. Indeed, 15 percent of 20-to-24-year-olds today report having had no sexual partner since they turned 18. (This is more than double the percentage for those born the 1960s; only 6 percent of them reported being sexually inactive at that age.)

Explanations abound. Some experts posit that porn and virtual sex are replacing the intimacy of actual sex. Others blame the distraction of social media, unrealistic expectations of beauty and sexual prowess perpetuated by the mass media, the pressure of preparing for careers, or the inhibiting effect of so many young adults living with parents.

Many worry about the emergence of a generation that fears the physical and emotional risks of sexual entanglements. Could we be headed for the world once described by science fiction writer Isaac Asimov, where people have become so accustomed to interacting with other humans only over their devices that robots must arrange reproduction to avoid extinction?

My own sense is that the changes in the sexual behavior of millennials are less dramatic and more positive. This generation is hardly embracing celibacy in significant numbers. Most of the increase in sexually inactive 20-to-24-year-olds occurred among women; much of this is probably due to their rising age of marriage.

At the same time, most millennials have never been the sexual players portrayed in the media, nor were the Gen-Xers. Still, they face an unprecedented romantic and sexual challenge. Never before have young people reached sexual maturity so early, had so much freedom to explore their sexual desires and identities, and yet had such strong incentives to postpone making long-term romantic commitments.

Hooking up at gatherings and having friends with benefits are two ways young people handle this challenge. Whatever the drawbacks of these practices, they are safer and less exploitative than many traditional ways of dealing with unsatisfied sexual desires, such as resorting to prostitutes or seeking one-night stands with strangers.

After interviewing more than 20,000 college students, sociologist Paula England and other researchers found that fewer than half of all campus hookups involve sexual intercourse. When intercourse does occur, it is typically between students who have hooked up before.

Furthermore, hookups are not replacing relationships. Most students hook up and date during their college years. Less than 10 percent reported having hooked up without ever going out on a date or being in a long-term relationship. More than one-quarter had never hooked up at all, but instead had dated or formed long-term relationships.

As an AARP-card-carrying member of the older generation, I am more impressed by the positive changes we see in the sexual behavior of teens and young adults today than by the negative behaviors that persist. Young people are initiating sex later than their peers did in the aftermath of the sexual revolution of the 1970s. They are taking more precautions, whether by having fewer partners or practicing safer sex. The ever-widening acceptance of consensual sex has been accompanied by a much more definitive rejection of non-consensual contact. The incidence of rape and sexual assault has fallen dramatically since the 1970s.

True, in recent decades, sexual frequency among couples has declined in several countries. Distraction by computers, smartphones or work pressures may be part of the story. But another part may be the fact that women today enjoy more equal status in their relations with men and feel more comfortable saying no.

One group of Gen-Xers and millennials, moreover, seems to have discovered a new secret to sexual happiness. Among heterosexual couples married since the early 1990s, those reporting the highest marital satisfaction — and the most sex — are couples who share housework and child care. In fact, these egalitarian couples are the only couples having more sex than their counterparts in the past.

So perhaps we should spend less time worrying about millennials’ sex lives and more time following the models they seem to be pioneering. Don’t feel pressured to have sex unless you really want to. Don’t feel embarrassed about having consensual sex whenever you want to, with whomever you want to, without feeling you need to commit to either the partner or the “lifestyle.” But when you do commit, don’t settle for anything less than the equality that forms the basis of long-term erotic and emotional satisfaction.