If you’ve ever had a partner play away from home, you’ll know that the sting is *real.* But is human biology hardwired for infidelity?

Pop culture and peer pressure often make us feel as though love, sex, and relationships are all supposed to happen to everyone at a prescribed time and in just the right order. And when they don’t, society can make you feel like the problem isn’t that one-size-fits-all relationship boxes aren’t for everyone — it’s that you must be doing it wrong.

But that’s not reality. In fact, not all people are meant to be in monogamous, long-term relationships all of the time. And there’s a whole body of scientific evidence that supports having a more open mind about monogamy.

Are you one of those people? Is your significant other? What do you even do with that knowledge? Here, therapist Susan Pease Gadoua, LCSW, founder of the Changing Marriage Institute and co-author of The New “I Do,” and sex and relationship therapist Joe Kort, PhD, help us comb through the research to get to what matters.

Nowadays, some are, some aren’t. But what does our biology say?

You’ve probably heard the standard evolutionary biology theory that females seek stable, long-term commitment from males because child-rearing leaves them vulnerable. Males, according to the same theories, seek to spread their seed far and wide. Is this really the case?

But males in some species have evolved to be monogamous nonetheless. That could be to prevent males from killing their offspring, as one group of anthropologists recently suggested.

It’s more than biology that drives humans, though, and these theories don’t take into account LGBTQ relationships. Evolutionary theories should really be seen as only a tiny part of the larger puzzle, given that we no longer have to worry about survival in the same way as our ancestors did.

Still, there are ways in which therapists see concepts of infidelity play out in couples regardless of sex, gender, or orientation.

Kort says that his male clients, whether in gay or straight marriages, seek to have open relationships or extramarital affairs more often than his female clients.

“I’m inclined to think it’s testosterone,” Kort says, before countering his own theory by adding, “The newer thinking is: men just have more social permission to cheat, and women traditionally haven’t. Women are gaining permission, and that might change.”

Gadoua also says that more of the men she works with wind up cheating than women do. And she’s seen one slightly horrifying trend (which may or may not be part of an evolutionary drive) in new parents:

“After a baby is born, that’s a high-risk time for men to be having an affair,” she says. “I’ve seen something happen to men where they don’t want to be tied down.”

Motherhood has the opposite effect on some of Kort’s clients. “I frequently see this in my practice. Where a couple is open, they’re having kinky sex, open sex, poly sex, or whatever. Then a child is born, and the woman tends to not want that anymore. It’s very disconcerting to the male, and this is not at all the same in gay couples.”

But the roles may reverse later in life, according to Gadoua. “When women enter menopause, their estrogen levels go down,” she explains. “Estrogen is the caretaking hormone. One of my clients said, ‘I’m tired of taking care of everyone else. I want my time.'”

The idea that more men than women cheat may also be changing as our culture rapidly changes.

Given that more women work and achieve positions of power than at any other time in history, these demographics may now be shifting, says Alexandra Stockwell, MD.

“There are many reasons for this, including that co-workers get to know one another well and often spend more time together than spouses do,” she says.

While evolution may have passed down the notion of monogamy to some of us, that’s certainly not universal. Aside from the fact that many cultures practice polygamy, the evidence that some of us may be geared toward multiple partners is also in our genes.

One study found that some people with a specific type of dopamine (the pleasure-reward neurotransmitter) receptor gene reported being more sexually promiscuous and were 50 percent more likely to cheat on a spouse.

Scientists in Finland also looked at a gene that’s responsible for receptors of vasopressin and observed that having lots of vasopressin receptors correlated with women’s infidelity — but not men’s.

“The research is clearer and clearer that we are wired to be nonmonogamous,” Kort says. “We make choices to be monogamous on purpose for children, family, or property.”

Gadoua notes that her patients’ parents have also strongly influenced their views on relationships. “Parents unconsciously say or do things that give children the idea that they don’t really have to commit, or the opposite,” she says. Perhaps the parents do that because they’re wired to as well.

A recent study in Wales tested how perceptions of wealth might influence men and women to want long- or short-term relationships.

After being shown photos of mansions, jewelry, fancy cars, and gold, the test subjects were asked to rate photos of models based on whether they would choose them for long-term relationships, short-term relationships, or no relationships at all (basically a lab version of “F*ck, Marry, Kill.”)

Both men and women chose significantly more short-term partners than the control group that just saw photos of potted plants and groceries.

While hardly definitive, this study may indicate that notions of wealth make us more likely to consider cheating. Let’s not overstate the causality here: This research doesn’t show that income leads to cheating. But the findings of this study suggest a link.

“If somebody worries about having enough food on the table and shelter, they may be less likely to have unstable relationships,” Gadoua reasons.

“But if somebody finds a partner who meets their basic needs, and they aren’t worried about paying the bills, then they do tend to think about luxuries and having more choice in their life.” This could dovetail into infidelity.

Another study that shows men in heterosexual marriages who aren’t the primary breadwinners are more likely to cheat. Gadoua has seen this happen with clients: It seems that some men still subscribe to the old definition of masculine identity and acting as the household’s main provider.

“Having an affair may be a way to get some validation that they’re not getting from the workplace,” she says of these men. According to Gadoua, younger couples seem to have a better handle on this.

“Now, younger people often wait until they’ve got their life together on their own and then make the decision to get married,” Gadoua says. “I definitely think that if any couple can have a conversation about expectations in roles and contributions before getting married, they will stay more faithful.”

In particular, Kort has observed gay male couples thriving in successful open relationships.

Judging by the few scientific studies about the quality of open and polyamorous relationships, the outlook is good. A survey at the University of Quebec demonstrated that there are no differences in relationship satisfaction, sexual satisfaction, trust, or commitment between people in polyamorous, open, or monogamous relationships.

In terms of biological differences, an earlier study from 2007 found that both males and females who prefer to have multiple partners also have higher levels of testosterone than those who prefer a one-and-only. High testosterone levels *might* have links to cheating behaviors.

But let’s remember to take this with a grain of salt. Higher testosterone levels may be part of an underlying factor but don’t lead to the behavior itself.

If a relationship looks like it’s heading to a deeper level of commitment, it’s important to set boundaries around monogamy and involving others in your sex life.

What can you say if you know you’re likely to cheat?

It’s easy to think you’re ready for a difficult conversation until it happens. So, what’s the best approach?

“It absolutely can help you have more honesty and transparency in your relationship,” Gadoua says. “If you say to the other person, ‘This is something I know about myself, so I’m willing to be monogamous right now, but I don’t know that I always will be able to,’ then that person has the choice to get married or not.”

You’re likely to create a pile of wreckage with an unexpected affair if you know this about yourself and don’t share it.

What if you’re expecting commitment?

If you’re someone who wants a completely monogamous commitment, this is your chance to proceed with caution or keep shopping for someone who wants the same. It might not sound romantic, but open communication may be the key to long-term happiness.

Biology has possible links to the motivation to cheat. But the studies are small, and there are so many ways in which biology has an increasingly small impact on what we do.

It’s easy to bat around the idea of infidelity and biology/psychology being bedfellows. But if you establish your boundaries and expectations before making any long-term commitments, you and your partner(s) will know where you stand. This allows you to make considered decisions within your relationship.

Sabrina Rojas Weiss lives in Brooklyn, surrounded by her fellow freelance writers and competitive stroller-pushers. Follow her on Twitter @shalapitcher.