part0009

J ohn Gray’s Men Are from Mars, Women Are from Venus is one of the best-selling books of all time. Its central premise—that men and women are so dramatically different in their psychology that we might as well think of them as coming from different planets—resonated with the American public in the 1990s. They purchased the book in droves, just as they did for Gray’s follow-up sex manual (Mars and Venus in the Bedroom ), which argued that, when it comes to sex, men and women have completely different physical and emotional needs. There’s just one problem with both of these books: they’re based on stereotypes, not science.

Men and women are not polar opposites when it comes to their sexual psychology. As you’ll see in this chapter, most of the things that men fantasize about, women fantasize about as well—and vice versa. For example, gender stereotypes suggest that threesomes and group sex are typical fantasy themes for men but not women. These stereotypes also suggest that romance is a typical female but not male fantasy. However, the truth of the matter—and what my survey results reveal—is that most men and women have had both types of fantasies before. This tells us that there’s actually a lot of commonality in what people desire when it comes to sex, regardless of their gender identity.

However, it’s not fair to say that we’re exactly the same, either. It’s definitely not the case that men and women are identical with respect to what they fantasize about the most or how often they do it. For instance, although most men and women have had group-sex fantasies, men are more likely to have them, and they have them more often. Likewise, although most men and women have had passion and romance fantasies, these fantasies are more common among women, and women have them with greater frequency. These differences are nowhere near Mars and Venus proportions, but they still tell us something important about our sexual psychology. Therefore, we would be wise to take a close look at them.

Before we do, though, let’s first dispense with the idea that the existence of a gender difference implies that one gender is somehow better than or inferior to another. Speaking about gender differences in any capacity has become increasingly controversial. In fact, I know a lot of scientists who won’t speak publicly about any gender differences at all out of fear of backlash! That’s problematic. Scientists shouldn’t be afraid to talk about their data, and the public shouldn’t be so quick to bash scientists who publish research that reveals politically inconvenient or uncomfortable truths. We need to be willing to consider data that challenge our worldview instead of burying our heads in the sand or just picking and choosing which scientific studies we’re going to believe and which ones we’re going to ignore. To the extent that we simply dismiss every study that challenges our beliefs as “fake news,” we’ll never truly understand how the world works. We’ll also miss out on countless opportunities to apply science in ways that can better our lives.

The problem with discussing gender differences isn’t really that we are afraid of finding out that men and women might be different—it’s that we’ve been conditioned for far too long to believe that stereotypically feminine interests and desires are inferior and stereotypically masculine interests and desires are superior. That’s the kind of thinking that’s dangerous and that we should be standing against, not the very idea that gender differences themselves represent problems. As we go forward in this chapter, try to keep an open mind and remember that difference isn’t a dirty word.

Before we start exploring gender differences in sexual fantasy, it’s important to step back and define a couple of key words and concepts. This will help you to better appreciate what some of the differences mean and where they might come from. In particular, it’s essential that you understand the meaning of the terms sexual orientation and sexual flexibility. First, sexual orientation is something inborn that “orients” us toward a certain sex—usually toward women if you’re male, and usually toward men if you’re female. There’s an abundance of genetic and neuroscience research suggesting that sexual orientation is influenced by biological factors early in life, especially the type and amount of sex hormones we’re exposed to in utero. 1 These hormones affect the development of the brain in numerous ways and ultimately lead to several important differences in brain structure and function between people who are attracted to the same sex and those attracted to the opposite sex.

Now, this isn’t to suggest that prenatal hormonal exposure can only lead to two outcomes: a “gay brain” or a “straight brain.” Biology is never so simple and predictable. Not only are we all exposed to different levels of hormones during fetal development for multiple reasons—including but not limited to variations in our mother’s stress level, medication use, diet, and environment—but we also vary in our individual sensitivity to those hormones. As a result, our brains—and our sexualities—end up falling along a spectrum rather than existing as two discrete classes. The analogy I like to use is that we have two dials in the brain, one that controls attraction to men and one that controls attraction to women. In some cases, hormonal exposure turns one of these dials way up, resulting in a very strong orientation toward a particular sex. And if that dial is turned all the way up, perhaps it prevents the other dial from moving at all. In other cases, though, both dials might be turned to different degrees, with the end result being some variant of bisexuality. And in yet other cases, neither dial moves at all, resulting in a total lack of sexual attraction, or asexuality.

In short, sexual orientation is the degree to which we are biologically predisposed to desiring men, women, both, or neither. In order to facilitate reproduction and the survival of our species, though, most people wind up with a moderate to strong orientation toward the opposite sex—an orientation that emerges around puberty and remains relatively stable throughout one’s life.

By contrast, sexual flexibility is a totally separate aspect of the sexual brain that operates alongside our sexual orientation. To go back to my earlier analogy, think of sexual flexibility as a third dial that can be turned completely, partially, or not at all. Sexual flexibility is a willingness to deviate not only from our sexual orientation but also from what our culture and society have told us we should want when it comes to sex. In other words, it’s our degree of comfort with trying new things and bucking sexual norms. We all have some degree of sexual flexibility—it’s just that some folks only have a little, while others have a lot. For those who are low on flexibility, their sexual orientation will appear pretty stable over the life span, barring some extraordinary circumstances. For instance, consider a man with a strong heterosexual orientation who is low on sexual flexibility (in other words, his flexibility dial is just slightly turned up)—he might ultimately have sex with other men, but only if his access to female partners is severely limited, such as if he is in an all-male prison, attending an all-male boarding school, or stranded on a desert island where there are no women around. If his testosterone levels are high enough, he’s feeling horny, and he is unable to obtain partners of the sex he’s oriented toward, he may pursue same-sex contact—but, again, only in the most extraordinary of circumstances. Now, if we instead imagine that this same man has a high degree of sexual flexibility (that is, his dial is turned up as high as it goes), he might not need such extreme circumstances to pursue same-sex contact. For instance, if his female partner really wants to have a threesome with another man, he might readily oblige. Or if he is single and finds himself the object of affection of a gay man he meets at a party, he might agree to receive a blow job after having a drink or two. However, it’s important to note that he’d still wake up heterosexual the next morning in both cases, because his strong underlying orientation toward women would not have changed. (Remember, orientation is controlled by totally different dials.)

Your degree of sexual flexibility therefore says a lot about who you’re willing to have sex with and under what circumstances. However, sexual flexibility is also, to some extent, a general willingness to try to new sexual things—especially things that might be socially or culturally forbidden. This idea—that sexual flexibility isn’t limited to the gender of your partner—is not something that many other scientists have previously argued, but it’s something that’s strongly supported by my survey data. When I looked at participants who said that they were either exclusively gay or straight, I found that those who had fantasies about same-sex contact were more likely to have a whole host of other sexual fantasies that deviate from what many people consider “normal.” For instance, they were more likely to fantasize about being with partners of different races, engaging in BDSM sex, having group sex, and being consensually nonmonogamous, among other things. In other words, we’re talking about a very general erotic flexibility here that goes well beyond being flexible about the gender of one’s partner. It includes flexibility with respect to other partner characteristics, such as race, as well as flexibility in terms of trying new sex acts, such as BDSM.

Got it? Good. With these definitions in mind, think back to when we talked about homoeroticism fantasies. If you’ll recall, I found that nearly two-thirds of women who said they were exclusively heterosexual had same-sex fantasies; by contrast, the number of exclusively straight men who had same-sex fantasies was less than half that. This tells us that women’s fantasy partners are less likely to match up with their sexual orientation compared to men. Why is that? As I’ll explain below, scientists believe it’s because women’s sexual flexibility dials tend to be turned up higher than men’s.

A lot of Americans are under the impression that all women are secretly bisexual—men, not so much. In fact, a lot of people question whether male bisexuality is even a thing. This kind of thinking reminds me of scene from the classic television series Sex and the City in which Carrie Bradshaw famously mused, “I did the ‘date a bisexual guy’ thing in college, but in the end they all ended up with men…. I’m not even sure bisexuality exists. I think it’s just a layover on the way to gaytown.” 2

The truth of the matter is that both of these beliefs about bisexuality—that all women are bi and all men are either straight or gay—are incorrect. Men can indeed be bisexual. And while women are more likely than men to be bisexual, it’s far from the case that all women are. The reason we perceive bisexuality as being so common among women isn’t necessarily that women are more likely to have both of their sexual orientation dials turned up. It’s that their third dial, the one that gives them their sexual flexibility, is usually turned up a little higher than men’s. There is a large and growing body of research supporting this idea.

Much of the research in this area has focused on how our genitals respond when we’re shown different types of pornography. 3 The way these studies usually go is that men and women are first hooked up to devices that record changes in blood flow to the genitals. Specifically, men are given a circular ring to put around the penis that records changes in erection size, whereas women are given a tampon-shaped device to insert in the vagina that measures blood flow to the vaginal area by emitting light and recording how much is reflected back via a photocell. Basically, as more blood flows to the vaginal tissues, more light is reflected back, and that is registered as increased arousal. Once these devices are in place, participants watch a series of brief porn videos in a random order, usually separated by some nonarousing nature videos.

The typical pattern that emerges is that straight men show the strongest arousal to lesbian porn. Of course, they show significant arousal to heterosexual porn, too; however, they show relatively little arousal when watching gay male porn. (Except for the really homophobic “straight” men—it turns out that a lot of them are actually turned on by videos of dudes getting it on. In other words, some homophobes doth protest too much. 4 ) Likewise, gay men show the strongest arousal in response to gay porn. They show significant arousal in response to heterosexual porn as well, but—not surprisingly—lesbian porn doesn’t do much for gay guys.

By contrast, women—especially heterosexual-identifying women—tend to show substantial genital arousal in response to all kinds of porn, regardless of the gender of the actors in the videos. This pattern suggests that women’s arousal is fairly flexible, whereas men’s seems to be more fixed with respect to their partners’ gender.

As further support for this idea that women have a more flexible sexuality, study after study has found that women’s sexual behavior is more variable than men’s over the course of their lives. For example, in his review of more than forty years of research on differences in male and female sexual behavior, social psychologist Roy Baumeister discovered that—among other things—women are more likely to have a same-sex experience in prison than men, despite what the popular media might lead you to believe (Orange Is the New Black notwithstanding). 5 Likewise, among people who are into swinging and group sex, he found that same-sex experiences are far more common among women than men.

So what does all of this mean? Why do women seem to be more flexible when it comes to the gender of their partners? Some have argued that there’s a cultural explanation. Because male homosexuality has, at least in recent history, been more socially reviled than female homosexuality, perhaps men’s sexual fantasies and desires are more inhibited with respect to partner gender. In other words, perhaps men have been the targets of greater cultural conditioning. However, one piece of evidence that argues against this point is that, when you look at genital arousal patterns of male-to-female transsexuals, their responses don’t match up with those of women—instead, they look more like those of men in that they show far more arousal to one gender than the other. 6 In light of this, some have suggested that the underlying reason might be biological or evolutionary instead of cultural.

One evolutionary hypothesis is that it was adaptive for women to evolve a flexible sexuality because this would have assisted our female ancestors in cases where their male partners abandoned them or were killed. 7 Think about it this way: thousands of years ago, it would have been difficult for women to survive alone if they were pregnant or had children by a man who was no longer in the picture (e.g., if the guy died or went to shack up with someone else). Finding a man who would be willing to make the sacrifices necessary to raise another man’s children would have been challenging; hence, some scientists have argued that it would have improved women’s (and their children’s) odds of survival if women could reorient their attraction to other women, effectively doubling their potential pool of alternatives for partnering up and sharing responsibilities.

Another evolutionary hypothesis is that perhaps women’s greater sexual flexibility evolved in response to men’s greater social power. 8 The basic idea is that, throughout most of recorded history, men have held more power over women economically and politically. They’ve also typically held more physical power due to sex differences in strength and size. According to this reasoning, perhaps women became more erotically flexible in order to reduce the risk of harm being inflicted upon them during sexual disputes with men. Put another way, holding lesser power for so many millennia may have led women to become more sexually flexible in the interest of survival and self-preservation.

Yet one other possibility is that perhaps men and women have different sexual imprinting windows, periods of time during which one can learn new sexual interests. Some scientists believe that men undergo a very brief sexual imprinting period during adolescence and that, once the imprinting window closes, it becomes harder for them to develop new sexual interests. Another way to think of this is that maybe men tend to experience something that dials down their sexual flexibility at a young age. For instance, perhaps the hormonal surges boys experience during adolescence have the potential to turn their flexibility dials back a bit, or maybe turn them off completely in some cases. The appeal of this theory is that it helps to explain why so many men with fetishes can trace them back to a very early sexual experience, such as trying on their mother’s shoes or fooling around with the family pet. Another advantage of this theory is that it can help to explain why men are more likely to engage in bisexual behavior during adolescence than at any other time in their lives. Many are skeptical of this theory, though, because the evidence is based almost entirely on retrospective recall of previous sexual behaviors. Maybe it’s just easier to recall early sexual experiences that are consistent with our current interests and desires because those experiences are more salient in our memories. This raises the question of whether early sexual experiences shape our desires or whether our desires shape what we remember of our early sexual experiences and how we label and interpret them. Of course, maybe there’s a bit of both going on.

We can’t say for sure which, if any, of these explanations is correct, or whether there’s potentially some truth to all of them. However, what’s clear is that there are multiple theories—both cultural and evolutionary—that could potentially account for the consistent observation that women seem to have greater sexual flexibility than men. These theories help to explain my survey results showing that women, particularly those who are heterosexual, are more malleable with respect to the gender of their fantasy partners than men. However, they also help to explain a number of the other gender differences in fantasy content that emerged in my survey. Below, we’ll take a look at some of the other differences that I discovered and consider how women’s greater sexual flexibility might explain them; of course, as you’ll see, this isn’t the only way to explain all of these gender differences. In fact, some of the gender differences we’ll explore might be due to factors that have little—perhaps nothing—to do with sexual flexibility.

I asked my participants to rate how arousing they found each of the following aspects of their favorite sexual fantasy of all time: the specific sex act that took place, the person(s) they had sex with, and where they did it. I then compared men’s and women’s answers. What I found was that there were no overall gender differences when it came to how they felt about what they did. That is, men and women rated the sex act itself as equally important in their fantasies. The who and where questions were a whole other story, though.

On average, men reported more arousal from who their fantasy partners were than women did. I drilled down into specific kinds of fantasies to see whether this pattern was consistent, and it was—in every type of fantasy in which there was a gender difference, it was always men who were more aroused by whom they were having sex with. Why is that? Well, the idea that women have greater sexual flexibility than men provides one compelling explanation. If women’s sexuality is simply more flexible by nature, then it makes sense that, when it comes to their sexual fantasies, the details of the person(s) they’re having sex with shouldn’t be quite as important.

There’s at least one other way of explaining this finding, though, and after reading through the thousands of fantasies I collected, it seems pretty plausible, too (it’s also consistent with previously published research on sexual fantasy): women appear more likely than men to see themselves as the object of desire in their sexual fantasies. 9 Therefore, having a specific person in mind may not matter as much to women because they themselves are usually—though certainly not always—the focus of the fantasy, not their partners. By contrast, it appears that men are more likely than women to view their fantasy selves not as objects of desire but as acting on an object of desire, which would make having a specific partner in mind more important for men.

With that said, it’s worth noting that there are certain kinds of fantasies where men and women care equally about who their partners are. For example, when looking at passion and romance fantasies, no gender difference emerged when it came to the importance placed on the partner. This makes sense, given that feelings of romance and passion are usually tied to a specific person—those aren’t emotions we usually feel for completely random or anonymous people.

When it came to where their fantasies took place, women cared more about the setting than men. And, again, when looking at specific types of fantasies, the direction of the gender difference was consistent every time it emerged. So why does the setting matter more to women than to men, especially if women have a more flexible sexuality? I suspect it has something to do with another gender difference we’ll explore later in this chapter, which is that women are more likely to have emotion-based fantasies than men. Having a specific setting in mind may be important for creating a certain tone or mood that helps to ensure a particular emotional need is met. Consistent with this reasoning, I found that the more importance participants placed on the setting, the more likely they were to have fantasies about meeting emotional needs. To be clear, this is not to say that the setting always matters more to women than men. For instance, in the case of group sex, BDSM, and romance fantasies, men and women rated the setting as equally important (or, to be more precise, unimportant). This is likely because the key elements of those fantasies are the sexual activities and/or people—not where the sex takes place. In other words, while women may derive more arousal from fantasy settings on average, women don’t always place more importance on the location than men.

When the first film adaptation of the popular BDSM-themed novel Fifty Shades of Grey landed in movie theaters, the audience largely consisted of women—in fact, they made up more than two-thirds of ticket buyers on opening weekend! 10 What accounts for this? My survey results offer some insight: women have more BDSM fantasies of almost every type than men. Therefore, it only makes sense that a phenomenon like Fifty Shades wouldn’t have equally strong appeal for both sexes.

So why do women fantasize about almost all of these forms of kinky sex more than men? This is another difference that can potentially be explained by women’s greater sexual flexibility. Recall that sexual flexibility isn’t just about being flexible with respect to who your partner is—it also includes flexibility with respect to sexual activities. However, that’s not the only possible explanation. It could also be that women’s greater interest in BDSM might have something to do with the idea that women are more likely than men to fantasize about being the object of desire. For example, if you think about something like bondage, well, being tied up is the epitome of becoming a sex object, especially when you think back to some of the sample bondage fantasies we considered earlier in this book. This same reasoning could help to explain why women also have more discipline, submission, and masochism fantasies, because unquestioningly following orders, submitting to others, and receiving pain are all experiences that depersonalize us to some extent—they transform us from persons to objects. This same transformation does not occur in dominance scenarios, though, which was the one kind of BDSM fantasy that women had less of than men. So the overall pattern here makes sense.

The one survey result this women-as-objects-of-desire line of reasoning doesn’t quite explain is the fact that women actually reported more frequent sadism fantasies—that is, fantasies about giving pain—than men. This finding was quite surprising to me. Whereas sadism has long been thought to be an almost exclusively male sexual interest, my survey results suggest that women are actually a little more into it than men—at least with respect to the types of sadistic activities I inquired about, which focused on things like spanking, biting, and dripping hot wax on a partner. It’s possible the results might have been different had I had focused on more intense ways of inflicting pain, like whipping. While we can’t rule out this possibility, it’s important to note that the gender difference I observed in sadism fantasies was quite small and nowhere near as large as what I saw in the other areas of BDSM. For instance, women were twice as likely as men to say that they often have bondage fantasies and almost four times as likely to say they often fantasize about masochism. By contrast, women were just 17 percent more likely to report frequent sadism fantasies. It’s also important to note that, while most men and women had fantasized about sadism before, this element of BDSM was the one they both fantasized about least often. In other words, we’re dealing with a very small difference in a relatively low-frequency fantasy. Therefore, we should be cautious about overinterpreting it, especially given that this finding isn’t perfectly consistent with past research.

There’s at least one other theory that can help to explain why women find most kinds of BDSM more arousing than men, which is the idea that BDSM experiences offer an escape from self-awareness. 11 With masochism fantasies in particular, the physical sensations of pain can help to take you out of your head, thereby distracting you from any sexual hang-ups and anxieties that might otherwise diminish arousal. Given that women are more likely than men to receive cultural messages that they’re not supposed to like or want sex, sexual activities like BDSM that help to distract women from culturally induced sexual anxiety might be particularly appealing to them.

I asked my survey participants how often they had fantasies about meeting a wide range of emotional needs. These included receiving approval, feeling loved or appreciated, feeling sexually desired, being sexually irresistible, feeling reassured, feeling sexually competent, and emotionally connecting with a partner. Women reported having every single one of these emotion-based fantasies more often than men. However, this isn’t to say that men don’t have emotion-based fantasies at all or that they only have them on rare occasions—far from it! In fact, the majority of men I surveyed said they fantasized about meeting all of these emotional needs at least sometimes. For both men and women, feeling desired, sexually competent, and irresistible were the most common emotional needs they fantasized about meeting.

I should also say that both men and women were far more likely to fantasize about meeting emotional needs than they were to fantasize about emotionless sex. In fact, the vast majority of both men and women (more than 70 percent) said that they rarely or never have fantasies about emotionless sex. This tells us that our fantasies are more likely than not to have an emotional element to them, regardless of our gender. It also challenges gender stereotypes about the role of emotion in sexual fantasy. While women certainly have more emotional content in their fantasies than men on average, there’s still a heck of a lot of emotion in men’s sexual fantasies.

So why do women have more emotion-based fantasies? This is one case where women’s greater sexual flexibility doesn’t offer a compelling rationale. In fact, when I looked at my data, being more flexible with respect to the gender of one’s partner was not linked to having more fantasies about meeting emotional needs—just the opposite! Among exclusively heterosexual women, the more same-sex fantasies they had, the fewer emotion-based fantasies they reported. The same was true for exclusively straight men—more same-sex fantasies were linked to fewer emotion fantasies.

If sexual flexibility isn’t the explanation, then what is? One possibility is that women’s greater interest in emotion-based fantasies is learned. American women have long been the recipients of cultural messages that sex should be an inherently emotional experience for them and that they’re not supposed to want casual, no-strings-attached sex. So it could be that women have just been conditioned to think about sex in more emotional terms. Along these same lines, it’s also possible that fantasizing about emotional connection and fulfillment could be a way that some women relieve themselves of feelings of guilt or shame over sexual fantasies that involve culturally taboo activities. For instance, adding an emotional element to a casual-sex fantasy might lead to less guilt about desiring casual sex.

An alternative view is that perhaps women evolved to have emotion-based fantasies more often. Evolutionary psychologists argue that humans—like all other species—are motivated to pass their genes along to future generations; however, because reproduction is much more costly for women than it is for men, it makes sense that the sexes would have evolved different mating strategies that reflect the vastly different biological realities they face. For men, it would be adaptive to have greater ability to separate sex from emotion because this would increase their odds of pursuing mating opportunities with a wider range of partners, thereby enhancing their reproductive potential. For women, though, it would be adaptive to seek more connection between sex and emotion in the interest of promoting long-term relationships with men who are going to stick around and help care for any children they father. Thus, from the evolutionary viewpoint, it would make sense for women’s fantasies to be somewhat more emotional and less casual in general than men’s.

Up until this point, we’ve focused on the fantasy themes that are more common among women, including less emphasis on who their partner is (and their partner’s gender), more emphasis on the setting, more interest in BDSM, and more emotional content. Now let’s take a look at the fantasy themes that are more common among men.

So why is that? Evolutionary psychologists have argued that it has something to do with sperm competition. When men are in sexual situations in which multiple guys are having sex with the same women, their sperm are no longer just competing against each other to reach the egg first—they’re competing against other men’s swimmers, too. It is thought that men’s brains and bodies evolved to take action in these situations in order to help them compete more effectively.

Consider this: in a study in which researchers collected straight men’s ejaculate after they masturbated to one of two different pornos, they found that guys who viewed a gangbang scenario in which multiple men were having sex with the same woman released more active sperm than guys who watched a video of lesbian group sex. 12 In other words, it seems that men are unknowingly increasing the sperm level in their ejaculate in response to the specter of competition.

Scientists have also found that when heterosexual men suspect a female partner of having recently cheated, they engage in harder and faster thrusting the next time they have sex. 13 It seems that when men believe that another guy has had sex with their partner, they become more vigorous in bed. The thought is that these men are subconsciously trying to remove sperm that may have been deposited by male rivals—something researchers claim the human penis was designed by evolution to do. As some evidence for this idea, consider a study in which researchers took dildos of different shapes and sizes and stuffed them into artificial vaginas loaded with simulated semen. (By the way, should you need to make your own simulated semen, all you need to do is mix seven milliliters of room temperature water with 7.16 grams of cornstarch and stir for five minutes. As reported in a 2003 journal article, “this recipe was judged by three sexually experienced males to best approximate the viscosity and texture of human seminal fluid.” 14 ) The scientists found that the dildo that most closely approximated the shape of a real-life penis displaced the most simulated semen, particularly when it was thrust deeply. Put another way, men’s penises aren’t just vessels for depositing semen—they’re also tools for removing semen left behind by other men. However, to be most effective at semen removal, guys need to be extra energetic in bed, so it would make sense that sperm competition scenarios would generate high levels of sexual arousal and excitement in men.

Although evidence for the sperm competition theory is growing, it remains a somewhat controversial topic, and more research is needed. However, to the extent that it’s true, it offers a fascinating explanation for why men have more group-sex fantasies than women.

Men were also more likely than women to fantasize about the vast majority of taboo acts I inquired about on my survey, including voyeurism, exhibitionism, incest, and fetishism. And when it came to the most deviant and extreme fantasies, like pedophilia and bug chasing (intentionally contracting an STD), men far outnumbered women. I wasn’t surprised to find this because most research has shown that taboo sexual interests are largely, though certainly not exclusively, a male phenomenon. 15

There were a couple of taboo fantasies I inquired about that men and women were equally likely to report having: sex with animals, being a furry (dressing up as an animal to have sex), frotteurism (rubbing up against an unsuspecting stranger in a public place), and necrophilia (sex with a corpse). This runs contrary to previous studies showing that men are primarily the ones who have these particular interests. However, those studies were typically based on very small samples of people who had actually acted out these behaviors in real life. To the extent that men are more likely to act on taboo fantasies than women (or are more likely to be caught acting on taboo fantasies), this could explain the discrepancy between my findings and other studies. Interestingly, there was just one taboo on my survey that women were substantially more likely to fantasize about than men, which was being an adult baby (dressing up, acting like, and/or being treated as an infant). However, this makes sense because adult baby fantasies often involve themes of masochism and submission, such as getting spanked. Therefore, these fantasies might just be an outgrowth of women’s greater attraction to BDSM. With all of that said, my results suggest that women probably have more taboo sexual interests than we’ve been led to believe; overall, though, they don’t have quite as many as men.

So why do men have more taboo sexual fantasies? I suspect that a big part of the reason for this is that men tend to have more sensation-seeking tendencies than women. Study after study (my survey included) has found this to be the case—that men have a higher threshold for excitement and are simply more willing to engage in intense activities, including both those that are sexual and nonsexual in nature. 16 Before we go on, note that sensation seeking (which men are higher in) is distinct from sexual flexibility (which women are higher in). Sexual flexibility simply refers to a general openness to trying new things and deviating from sexual norms. Being open to new experiences (i.e., being sexually flexible) isn’t the same as preferring or needing intense experiences in order to get off. With that said, it would make sense that men would be more drawn to sexual taboos because violating them offers just the kind of stimulation and excitement that sensation seekers are looking for. So why are men more likely to be sensation seekers? Some argue that it’s due to gender stereotypes and cultural factors shaping men’s and women’s personalities; however, others argue that we simply evolved this way. From an evolutionary perspective, if sensation seeking in general were to assist men when it came to obtaining resources or competing for mates, then nature would have selected for this trait in men. Likewise, if sensation seeking is detrimental to women due to their higher cost of reproduction, then women should have evolved to be more averse to risks of all sorts.

So sensation seeking might open the door to men’s exploring more taboos in the first place; however, it’s important to note that once men start exploring taboo interests, they tend to stick. This may be because, again, men’s sexuality tends to be more fixed than women’s, meaning that once men develop a sexual interest, they tend to maintain it.

On a side note, men’s greater interest in sexual taboos might also have something to do with the fact that they’re more likely than women to have compulsive sexual tendencies. Several studies—and my survey—have found that men tend to be higher on sexual compulsivity and, further, that greater compulsivity is linked to more taboo sexual desires. 17 By “compulsive tendencies,” I mean sexual thoughts and behaviors that one struggles to manage—in other words, people with compulsive tendencies don’t feel like they have control over their sexual desires. While we don’t fully understand the reason(s) for this gender difference in sexual compulsivity, one thing we do know is that not everyone who feels their sexual urges are out of control truly has compulsive tendencies. I say this because research has found that people who feel morally conflicted about their sexual desires have a tendency to label those desires as being “out of control.” 18 What this means is that the link between taboo interests and perceived sexual compulsivity sometimes reflects nothing more than moral qualms with one’s fantasy content. Consistent with this idea, the men who took my survey reported feeling more guilt about their sexual fantasies on average than women. This finding probably strikes many as counterintuitive, given that we live in a world where women tend to be judged more harshly than men just for being desirous of sex. Nonetheless, what this tells us is that perhaps part of the reason many men with taboo desires report feeling as though they can’t control their sexual urges is that men are simply more ashamed of their sexual desires than are women.

One final type of sexual fantasy where there was a major difference between men and women was in the area of gender-bending. Whereas women seem to be more flexible than men when it comes to experimenting with their sexual orientation, men seem to be more flexible than women when it comes to experimenting with their own and their partners’ gender identities. Not only do men fantasize more often than women about having sex with partners who are cross-dressers or transsexuals, but they also fantasize more about bending their own gender through cross-dressing or physically changing their bodies. Something that may surprise you about both of these kinds of fantasies is that the men who are most likely to have them are heterosexual—not gay or bisexual.

Let’s talk first about men who are into gender-bending partners. In psychological terms, these guys are known as gynandromorphophiles (how’s that for a tongue twister?), which is basically an elaborate way of saying they’re into sex partners who possess both male and female physical characteristics. Again, to be clear, research finds that these guys mostly identify as heterosexual, and genital-arousal studies comparing gynandromorphophilic males to heterosexual and homosexual men finds that their arousal patterns look more like straight guys’ than gay guys’. 19 In other words, they are more aroused by images of women than they are by images of men—however, more than anything else, they are aroused by photos and videos of people who have both male and female physical characteristics—people who are often referred to in the porn world by the very non-PC term she-male.

The appeal of gynandromorphophilia is thought to stem from what neuroscientists Ogi Ogas and Sai Gaddam have termed erotical illusions: unique combinations of sexual cues that, together, produce an extremely intense state of sexual arousal—far more than they would stimulate on their own. 20 In other words, when you combine strong physical cues of both masculinity and femininity, the result can be a very powerful erotic stimulus. But why would this affect men more than women? According to Ogas and Gaddam, it could be because men are more erotically responsive to visual sexual cues than women, something that could also explain why men in general tend to watch so much more porn. However, other scientists have questioned this explanation, arguing that the idea of men being more visually aroused is a myth and that men’s greater porn-watching stems primarily from the fact that most porn is made by men, for men.

Now, let’s address the guys who fantasize about bending their own gender. In psychological terms, they are known as autogynephiles, a term that refers to feeling sexual arousal in response to the thought or image of oneself as a woman. Psychologist Ray Blanchard has described four different types of autogynephilia, which vary in terms of the kinds of thoughts and/or behaviors that are sexually arousing: (1) wearing women’s clothing (i.e., cross-dressing), (2) acting or behaving in a feminine manner, (3) fantasizing about having female bodily functions, and (4) imagining having a woman’s body or body parts. 21 Autogynephilic men can be attracted to men, women, both, or neither—it does not necessarily say anything about their sexual orientation.

Many psychologists argue that autogynephilia is one type of transsexualism. However, it is important to clarify that not all male-to-female transsexuals are autogynephiles—thus, it is not the case that every natal man who desires to become a woman does so because he is sexually aroused by the thought of seeing himself as such. Most transsexuals are probably best described as being motivated not by sexual desire but by feeling trapped in the body of the wrong sex. Also, given all of the varieties of autogynephilia that have been described, it is not accurate to say that all autogynephiles are transsexuals, either.

The origins of autogynephilia and why men are more likely to be aroused by the thought of becoming the other sex are not well understood. However, when you think about it, violating gender roles and expectations has historically been a major social and cultural taboo, so perhaps this desire stems from men’s greater tendency to develop taboo sexual interests more generally. As some support for this idea, I found that the men who reported autogynephilia fantasies were more likely to report having almost every other taboo fantasy I inquired about. So whatever draws men to the taboo in the first place may also draw them to autogynephilia. In addition, I found that autogynephilia fantasies were related to reporting more compulsive sexual tendencies. Although this association was small, it is consistent with the idea that taboo interests may persist in some men because men are more likely to report compulsive sexual urges. Or maybe it just signifies that many men with autogynephilia fantasies feel morally conflicted about these desires, given that shame and guilt are linked more generally to labeling one’s sexual desires as compulsive or beyond one’s control.

One other interesting thing I discovered about autogynephilia fantasies is that they were related more generally to fantasies about becoming someone or something else entirely, such as being an adult baby or a furry. What do all three of these fantasies have in common? Well, they’re all fundamentally about escaping one’s sense of self. This suggests to me that men who are seeking an escape from self-awareness or reality might be predisposed to having not just autogynephilia fantasies but also a range of other fantasies about physical transformation.

You might be wondering whether there’s a counterpart to autogynephilia among women, and there is—it’s known as autoandrophilia, which refers to women who are sexually aroused by the thought or image of themselves as men. Far less is known about autoandrophilia than autogynephilia. In fact, Ray Blanchard, who did most of the pioneering research on autogynephilia, is on the record as recently as 2013 claiming, “I don’t think the phenomenon even exists.” 22 However, if the results of my fantasy survey are any indication, autoandrophilia most definitely is real, and it’s probably more common than Blanchard thinks. Indeed, I found that 11 percent of the women I surveyed reported sexual fantasies about becoming men and that 20 percent had fantasized about dressing up as men (although I should clarify that just 2–3 percent said they fantasized about these things often, meaning autoandrophilia rarely becomes women’s preferred fantasy content).

I would be remiss if I didn’t stop for a moment and acknowledge that there’s a lot of controversy surrounding the concept of autogynephilia. In fact, I know that just by writing about it I will invite some negative criticism and perhaps inspire some nasty book reviews. The critiques of this concept have been thoroughly addressed elsewhere and can be easily and freely accessed online, so I won’t get into them here except to mention that many in the trans community are uncomfortable with the very concept of autogynephilia because they see it as pathologizing for transsexuals due to the fact that it suggests an underlying sexual motivation for some members of the trans community. Some are also concerned that acceptance of this theory will set back the fight for transgender rights. While I certainly understand and appreciate these concerns, I am not able to ignore the accumulated evidence, which suggests that there are different types of trans persons: some who are autogynephilic, some who are autoandrophilic, and some who are neither. Though I believe the vast majority of trans persons aren’t autogynephilic or autoandrophilic, as a scientist, I think it’s important that we recognize this diversity instead of pretending it doesn’t exist just because we don’t like the implications.

With that said, let me be clear that I personally support a social agenda of trans inclusiveness. I believe that all trans persons deserve our respect and acceptance—and those who have a desire to undergo a physical transition should be able to do so because the evidence is clear that it doesn’t hurt; rather, it helps. 23 Moreover, I believe that trans persons deserve equal rights and should be able to live their lives as they please without be persecuted for doing so, regardless of whether they are autogynephilic, autoandrophilic, or neither. In short, I am a trans ally. However, I am also a scientist—and being a scientist means not letting my personal beliefs stand in the way of my ability to accept and report what the data say.

The conclusion I do not want you to take from this chapter is that, when it comes to sexual desire, men are from Mars and women are from Venus. We’ve certainly discussed a lot of ways that men’s and women’s sexual fantasies differ. We’ve also discussed how a lot of those differences may stem from fundamental underlying differences between female and male sexualities—most notably, the idea that women’s sexuality is more flexible than men’s. Attending to these differences is important because it can help us to better understand, for example, why men and women don’t always agree on what they want when it comes to sex and why they may find different kinds of pornography to be sexually arousing. That said, the fantasy worlds that populate our minds are much more alike than they are different. Please keep in mind that the seven major fantasy themes discussed earlier characterize both male and female sexual desire. Most men and women are fantasizing about the same things; the main difference is really in the frequency with which they have a given type of fantasy.