Alan, a 30-year old New Yorker, can summarize the sex-ed lessons of his Midwestern childhood with a few, strongly worded imperatives: Don’t have pre-marital sex. Get married. Then, have sex with that one person for the rest of your life. Alan heard these lessons not only at school—where, like 85 percent of public high school students over the past two decades, he studied abstinence-based sex-ed—but at church several times weekly, where his grandfather, a Methodist minister, preached about the sanctity of marriage. Back at home, he absorbed sexual health lessons from his mom, a nurse and sex educator, who translated government-approved facts like a “long-term mutually monogamous relationship with an uninfected partner is one of the most reliable ways to avoid STDs” and that “a mutually faithful monogamous relationship in context of marriage is the expected standard of human sexual activity” into “birds-and-the-bees” lessons.

“I was definitely programmed to think that the more promiscuous you are, you are going to get every STI,” said Alan. “You’re gonna die of AIDS.” But contrary to the warnings of authority figures, Alan has found that he’s still alive and HIV-free, even after dating multiple women at the same time as part of a polyamorous relationship. (”I’ve never had an STI.”) Part of the estimated 4 to 5 per cent of Americans participating in non-monogamous relationships, Alan is living proof that contrary to common belief (and virtually every officially-sanctioned sexual-health resource), non-monogamous people are just as likely to get STIs as more traditional couples. While there’s an increasing body of research to back this up, most people don’t realize that yet, trained by both secular and religious sources to see monogamy as the paragon of sexual health.

Such biases against non-monogamy are easy enough to detect. When a research team lead by psychologist Terri Conley at the Unviersity of Michigan asked 1,100 college students how they thought open relationships (or “consensual non-monogamy,” as sexologists call it) differed from monogamy, monogamous relationships were seen as better than non-monogamous ones on virtually every characteristic that the researchers thought to ask about (stability, trust, love, etc.). But by far the greatest differences was in perceptions of sexual health: Monogamy was perceived as a highly effective way to prevent spread of STIs; non-monogamy as a highly ineffective way. “I don’t want to catch any diseases,” said one 19-year-old when asked why he chose monogamy over an open relationship as his ideal arrangement. That many other students echoed his sentiment offered a clear takeaway: Monogamy is seen as synonymous with sexual health, while non-monogamy is a cesspool of disease.

To a certain extent, these students aren’t wrong. When executed perfectly, abstinence and monogamy are safer sexual health strategies than non-monogamy. But just like abstinence, perfect monogamy is easier said than done. Long gone are the days when saving oneself for marriage was the norm. Many new ‘serious’ relationships begin without any discussion of past history or testing results and without condoms. Other relationships that start out with condoms tend to ditch them after things begin to feel serious, rather than after actual STI testing. And since about 80 percent of Americans have more than a single sexual partner over their lifetimes, (and up to 30 percent have 15 or more) these less-than-safe choices tend to get repeated many times over.

Even once they get into a (presumably STI-free) long-term relationship, monogamists are not quite safe. Prevalence of infidelity is notoriously difficult to pinpoint scientifically, but some researchers suggest that up to 75 percent of all marriages (and a similar percentage of non-married partnerships) will eventually experience an infidelity. (Some anecdotal evidence: On the Casual Sex Project—an online forum for true hookup stories that I curate—about a third of the stories involve cheating on a partner.) So when we give up the wishful thinking of perfect monogamy and replace it with the more realistic idea of imperfect monogamy, is monogamy still better for your sexual health? Three recent studies suggest that it isn’t.

A second 2012 study by Conley surveyed more than 800 adults in both monogamous and non-monogamous relationships about their sexual health practices. They found that when monogamous people cheated on their partner, the hook-up wasn’t as safe as when someone in an open relationship did the same thing (albeit with permission from his partner). Alcohol or drugs were more likely involved. A discussion of STI status or prior partner history was less likely to happen. Condom use was rarer, and even when condoms were used, a follow up study showed that cheaters were less likely to use them properly. What’s worse, but completely unsurprising: cheaters were nearly three times less likely than non-monogamists to tell their primary partner about getting some on the side, which means their partners were less likely to know that they’d been put at risk. “People who are cheating want to believe that they were ‘caught up in the heat of the moment’ Conley suspects. “If they prepared for the possibility of the encounter by, say, using condoms, they would forfeit their right to say ‘I just couldn’t help myself!’”

It’s also likely that people who are non-monogamous are most accustomed to a culture of regular condom usage, safe sex, and communication about sex. “People who are consensually non-monogamous appear to be more aware of their sexual health risks,” says Justin Lehmiller, a Harvard psychologist (and Playboy contributor). “They not only communicate more with their partners about those risks, but they also practice safer-sex more often.” And it looks like those safer practices are paying off. In his yet-to-be-published study of 550 adults, he found that even though people in open relationships had more overall lifetime sex partners than those in monogamous relationships (six versus three), they were equally likely to have ever been diagnosed with an STI (20 versus 18 percent). In other words, people in non-monogamous and monogamous relationships have basically the same sexual health outcomes, despite having twice as many partners.

None of this comes as any surprise to people actively pursuing non-monogamous lifestyles. “We don’t even discuss condoms at parties,” my friend Vanessa, a sex-party devotee, told me. “There’s no need to. Everyone knows to use condoms with people who are not their primary partners. It’s just part of the game; it’s completely automatic.” Sam Glen, a 43-year-old male I interviewed while researching the sex lives of very sexually active people, adds that “condoms are absolutely fucking required with anyone who’s not a primary partner.” Glen had slept with more than 800 women when we spoke. “I’ve never had an STI,” he claimed.

This may sound unlikely, but despite what abstinence-only sex education programs are teaching America’s teens, condoms are remarkably effective at preventing most STIs. Mathematical models show that, given current prevalence of HIV in the U.S., you’re less likely to get HIV having condom-protected one-night stands with 4,000 different partners than you would during five years of condom-free sex with a single partner of unknown status.

Of course, many people don’t particularly like condoms. In one study of 900 sexually active young people, more than half reported that condoms were a cause of physical or psychological turn off. “It’s like a big piece of rubber you just put on your cock,” as one participant in a focus group study so eloquently put it. For many, being able to have regular safe sex without condoms is a major incentive to get into a monogamous relationship. However, non-monogamous (and, in particular, polyamorous) people have a solution for this as well: Get “fluid bonded’ with more than one person at a time. That means deciding not to use condoms with a regular partner after discussing sexual history and getting tested. For Alan and his two ex-girlfriends—who were all having sex with each other and were allowed to have sex with other people—that meant “getting tested twice, three months apart, with no other partners in between. And after that, if anyone wanted to have sex with other people, they had to exchange STI tests and use condoms for vaginal or anal sex.” If anyone broke this rule, they lost their fluid-bonded status until three months were up and they tested clean.

Of course, just because the rules are more liberal, doesn’t mean people don’t break them: cheating is entirely possible even in open relationships. Consensually non-monogamous relationships may better accommodate people’s needs to be sexual with others (and thus lower the need to cheat in an unsafe way), but they also attract people who are higher risk-takers and sensation seekers—people who may be more attracted to the rule-breaking aspect of cheating. Unfortunately, we currently know very little about how much rule breaking happens in open versus monogamous relationships and how that may impact sexual health. What’s more, all of the current data we have on safe sex practices and STI rates is based on self-report. We need studies that conduct laboratory STI testing to corroborate people’s claims before we can declare with certainty that people in open relationships do not suffer more sexual health issues than those in monogamous relationships.

For the time being, though, in the real world where monogamy is less than perfect, it appears to be no healthier than responsible consensual non-monogamy. “In the eight years that I’ve been doing poly, there have been only two instances where one of my partners or myself got exposed to an STI,” Alan says. “Both cases were from people in monogamous relationships who were cheating.” Luckily, they were using condoms, so they didn’t catch anything, but the threat—albeit a small one—is why Alan and his partners still gets tested at least every three months. Why, exactly, do they bother, given their minimal risk for infection? Alan, whose polyamorous lifestyle is far from the Biblical norm, chalks it up to what he was taught as a kid: “We are more on the conservative end of things,” he admits, pausing for a second to think. “Perhaps because of our strict religious upbringing.”