In the early 1970s our understanding of the course of

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Unformatted text preview: child simply waited for hands and words to shape it into a boy or a girl. But even before the 1950s ended, support for that view of sexuality began to fade. Near the end of that decade, a group of scientists studying guinea pigs discovered that early exposure to sex hormones had a major effect on sexual orientation of the brain.25 Similar observations in several other species followed. Hormones, apparently, in addition to shaping our genitalia, also shaped our minds, and that happened perhaps in the first few weeks and certainly within the first months of life. Soon after, another series of studies appeared showing that even prenatal exposure of 46,XX female infants to androgens (male sex hormones) produced girls and women with more masculine features and behavior.26 This further bolstered the idea that a piece of the sex puzzle lay inside human brains, and that piece was highly responsive to the hormones that bathed the fetus. In the early 1970s, our understanding of the course of human sexual development took an even more amazing and entirely unexpected turn. In 1971, a group of researchers described certain girls who, at puberty, seemed to become boys. An enzyme called 17-betahydroxysteroid dehydrogenase (17β-HSD) normally helps to convert androstenedione to testosterone in the developing fetus. Several different mutations can cause deficiencies in 17β-HSD. When that happens, there is less testosterone in the developing fetus. Because of that, most of these children—though 46,XY—are born with female genitalia and identified and raised as baby girls. But at puberty, many of these children begin to produce nearly male amounts of testosterone, develop phalluses much like penises, grow beards, acquire large muscles, and speak with the voices of men—they undergo a nearly complete reversal of sex.27 Then in 1974 another study appeared that described a second syndrome called 5-alpha reductase deficiency, or 5α-RD. This syndrome results from mutations in a gene encoding 5-alpha reductase (5αR). This enzyme is responsible for the production of another hormone essential for making baby boys. First, like boys with deficiencies in 17β-HSD, 32 Between XX and XY genetic males with 5α-RD are born with female external genitalia, and are consistently identified and raised as baby girls. And with 5α-RD, at puberty, these girls again become boys, or nearly so.28 Surprisingly, most children with deficiencies in either 5αR or 17βHSD manage the gender switch at puberty without medication. This means, to many, that the gender identity of these boys results from the combined effects of prenatal and pubertal hormones and not the psychosexual environment in which the boys grew up. Somewhere within that brew of hormones and genes and dolls and toy soldiers there may be some deep secret about how we all come to be who we are. Or maybe not. Regardless, two things are clear. First, no one has yet figured out the list of ingredients needed to make a boy or a girl—neither chromosomes, nor hormones, nor genes, nor family or society or chance, alone or in combination, seems sufficient to explain how one’s sex comes to be. And second, there is no hard reason why we’ve come to believe that people even need to be a boy or a girl, no hard reason whatsoever. The history of our wanderings in the maze of human sex makes for fascinating reading. But it does not make boys into boys, or girls into girls, or eliminate the gulf in between. 3 Sex Versus Reproduction: Why Are We So Married to the Idea of Two Sexes? How we think about one another has clearly changed drastically over the millennia. But there has been one constant—we’ve always been thinking about it. Sexual intercourse, the force that drives the planet, has been a preoccupation of people forever. And one thing was clear from the outset: reproduction involves intercourse. From Hippocrates forward (and, I’m sure, backward), people have understood that people came from people, and the sex act was responsible for that. But although it’s clear that reproduction inevitably results from intercourse, the inverse is not true: sexual intercourse does not always result in reproduction. What, then, is its true purpose? Could it be that sexual intercourse serves other purposes? In a class I taught, we used a book with the question “Why sex?” written in large letters across the back. On her flight home at Thanksgiving, one of my students was reading that book when the woman sitting next to her noticed the question and said, “The answer is simple—because it feels so good.” Sexual interactions do feel good. They taste good. They even smell good. Indoors or out; in the morning, afternoon, or evening; missionary style or otherwise; in the shade or in the sun; sex catches all of our senses and holds them hard and fast. And when it’s done with us, sex leaves us unclasping ourselves, struggling for breath, and weak as 33 34 Between XX and XY children. For most of us, nothing but sex can do that or any...
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This document was uploaded on 02/04/2014.

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