But for all the insight evolutionary psychology offers about the benefits of variety to the species, even the newest and best research about how individuals acquire a particular kink says that it is not designed or determined by evolution, but that it happens, possibly arbitrarily, through childhood experience. Which un-banishes Freud and puts him back at the center of things—a supermarket-checkout version of him, anyway, less obsessed with mothers but still focused on childhood as the source of sexual taste in adulthood. There’s all kinds of research out there, pointing in all kinds of directions, but when it comes to a person’s individual kink, “the leaning is toward learning,” says Daniel Bergner, whose new book, What Do Women Want?, contains the rat study above.
But how do we learn? In Perv, forthcoming this fall, the science writer Jesse Bering describes a man passionately obsessed with amputees. The man himself traces his ardor back to a time when he was 5 years old, sitting under the kitchen table while a man and a woman were visiting for coffee. The woman had a plaster cast on her leg, and beneath the table, her husband kept stroking it. “When is it coming off?” someone asked, and in the boy’s mind, these oddball components—romance, thrill, leg, off—were translated in adulthood into erotic yearning. In Bergner’s previous book, the excellent The Other Side of Desire, he tells the story of an adman named Ron who grew up in Queens and remembers being fascinated, also at about age 5, by the woman who ran a dress shop in his neighborhood. He would urge his mother to stop by the store simply so he might revisit the thing that haunted him: One of the woman’s legs had been withered by polio, and she wore a special, stumpy shoe. As an adult, Ron was a serial amputee dater before finding happiness with a woman who modeled for magazines specializing in amputee porn. “The cherry on the sundae is that she’s a double amputee, which brings me such happiness and joy.”
A fetishist who finds his or her way to a therapist’s office can usually tell a genesis story about the exact time and place that an interest in a certain kind of person or costume or texture took hold (though shrinks warn that such retrospective certainty does not signal actual causes, and that these desires can intensify or wane over time). Rubber fetishists can often vividly recall the training pants their younger siblings wore. There is hardly a transvestite—defined in the literature as a straight man whose sexual arousal depends on wearing women’s clothes—who doesn’t remember being dressed up in his older sister’s bras and panties. Enema fetishists, for whom the ultimate erotic act is to be splayed across someone’s lap with a rubber hose in their rectum, are rarer than they used to be, says Lehne, but those that do exist tend to be older Jewish men of Eastern European descent whose mothers used enemas to force the issue when their little ones didn’t poo on cue. The Other Side of Desire contains the story of a man with a foot fetish so overpowering that he found it difficult to listen to the weather report in winter; just hearing the words feet of snow could make him hard. He confided to a therapist that in second grade, ashamed that he could not read, he looked down at the floor to avoid being called on. There, he saw his classmates’ feet.
Freud talked about a latency period in childhood, from about age 6 until puberty, barren of sexual feelings or thoughts. He was wrong about that: Kids aren’t having sex at that age, usually, and they aren’t thinking about sex as sex, but they’re having all kinds of experiences that establish the boundaries for what the mid-century sexologist John Money called their “lovemap”—the range of things they end up liking and wanting in bed. (The fact that children may begin to develop that map as early as 8 or 10 may seem a little less weird when you consider that, until recently, the age of consent for girls was 12 or 13.) But why do some things nest in your proto-sexual psyche, while others slide by? Lehne has a theory that the foundation for an individual’s sexual taste is built when an encounter with a particular image or event overlaps with an activation of the autonomic nervous system—a quickening of the pulse, a prickling of the scalp, a panting, blushing, whole-body rush of feeling. These are the sensations that adults usually recognize as sexual arousal, and shame, fear, anticipation, and anxiety are the closest most children get. Which may be why so many kinks have a nursery-school flavor, related to poop and pee and bare, naked bums; to wanting and waiting and finally having; to who’s bad and who’s good and who’s going to get in trouble later. Lehne saw one patient who fantasized about cutting the penises of young boys with a knife. In therapy, Lehne learned that his mother once found him masturbating in the bathtub at 7. “Don’t do that,” she said. “You’ll hurt yourself.”