Date published: 2/13/2005

CHARLOTTESVILLE--Here is a true and horrifying story: In 1966, one infant in a set of identical male twins lost his penis in a botched circumcision. The parents consulted a Johns Hopkins University doctor, who recommended castration, construction of female genitalia, administration of female hormones, and raising the child as a girl. They followed this advice and renamed the child Brenda.

When Brenda was 12, her physician said she had adjusted well. Psychology and sociology texts, prominent feminists, and the media talked of the "opposite sex identical twins," one masculine and the other, Brenda, "remarkably feminine--neat and dainty." Her case was celebrated as evidence that sex roles are socially constructed.

These claims amounted to lies. Years later, a journalist found Brenda in Canada. Brenda had become a man, David, and was married to a woman. David had always acted like and wanted to be male and, at age 14, had started living as one. His parents had told him the truth when he was 15 and helped him get a mastectomy and male hormones.

Growing up as Brenda, he had ripped off the first dress put on him. When given a jump rope, he used it to tie people up

and whip them. He played with dump trucks and built forts, pretended to shave with his dad, and found the Rockettes sexy when at age 12 he saw them in New York. Brenda wanted to urinate standing up, and her elementary-school teachers remarked on her "pressing aggressive need to dominate."

The Brenda-David story ended horrifically. A couple of months ago, David committed suicide.

After the truth about Brenda surfaced, Johns Hopkins decided to look at 25 other males, ages 5 to 16, born without penises, castrated, and raised as girls. All loved rough-and-tumble play. Fourteen had declared themselves to be boys. Johns Hopkins found two males born without a penis but raised as boys. These two fit in well and were better adjusted than the others.

As sexual differentiation specialist Margaret Legato explains, testosterone in the womb makes a person think he is a male. It is useless to say to a child born a boy, "You are a girl."

This story reveals that getting nature/nurture answers wrong can be devastating. In fact, we are born masculine or feminine. Certain characteristics are largely built into us, not created by society or our families.

Three kinds of evidence indicate that men and women have different natures. First, male and female hormones change behavior.

Second, differences between men and women appear in cultures around the world: Men, in general, are aggressive and assertive, and women are nurturing. These differences do not seem to result from culture because they occur regardless of whether a culture is patriarchal or egalitarian.

Third, male and female infants and young children behave differently before society has had a chance to construct their identities. In infancy, for example, girls look longer at people while boys look longer at mobiles. Throughout life females tend to be relatively more interested in living things, especially people, and males in machines and non-human sciences.

Sex differences have been in the news of late because Lawrence Summers, president of Harvard, created a firestorm by wondering if biological reasons could help explain why a smaller proportion of women than men were reaching the very top of some scientific professions. He need not have wondered; there are biological reasons.

When extremely bright 12-year-olds take the SATs in math, 13 boys score above 700 for every girl who does. Even the girls who do score above 700 are far less likely than their male peers to go on in the heavily mathematical sciences. They want science and people and often become doctors. It is not an accident that as women thrive in sciences like biology and medicine, they are "underrepresented" in math and the more mathematical sciences.

As in the Summers controversy, some women express outrage at any suggestion of sex differences. I believe this is wrong-headed. Though both men and women would live better lives if we came to take sex differences more seriously, women would be the bigger gainers.

Take sex, for example. Testosterone regulates the male and female libido, and men have far more testosterone than women do. Men are more interested than women in sex and in a variety of sex partners. Programs like "Sex and the City" and "Friends" don't give young women a clue about this.

In and out of marriage, women say they engage in sex to share emotions and love. Men give reasons that are more narrowly physical, such as need, sexual gratification, and sexual release. Because young women so often think their sex is about a relationship while their partners think it is about sex, teen girls get hurt.

Seventy-one percent of teenage girls report being in love with their last sexual partner, but only 45 percent of boys do. And teen girls are far less likely than boys to report being happy with their sexual experiences and far more likely to report that they wished they had waited longer to have sex.

Women's greater emotional risks occur even in more mature women in established relationships. Cohabiting women, for example, report much less emotional satisfaction with their sex lives than do married women. They often expect marriage whereas men are far more likely to regard the cohabitation as a pleasant sexual and domestic interlude till something better comes down the road.

Women would also be the biggest gainers if we took sex differences seriously when considering work-family issues. Most women love to nurture children. Oxytocin, which promotes nurturing and bonding, has more impact on women than on men because women have more neural receptors for oxytocin, and they get still more during pregnancy.

On a 10-point scale, 86 percent of mothers rate their children a 10 for their importance to personal happiness; just 30 percent of employed women rate their job as a 10. Ninety-three percent of mothers regard their children as a source of happiness all or most of the time; 90 percent say the same about their marriages. Of working women, however, only 60 percent find their careers a source of happiness all or most of the time.

The latest research shows that day care makes many children more aggressive and some less smart and that breast milk raises IQs and wards off a host of diseases. But our school textbooks and best colleges send women the message that they are wasting their talents if they are not full-blown careerists. Thus, after giving birth, they are meant to hurry back to full-time work after leaves of a few months.

It is often said that families need two breadwinners. Yet the median male worker now makes 30 percent more than he did in the 1950s in real inflation-adjusted dollars.

Compared with just a few years ago, a higher proportion of new mothers are staying home for a year or more after giving birth. The trend is strongest among the best-educated women. Though there is much media attention given to the new nurturing father, there are still 58 housewives caring for minor children for every one househusband.

In the future, I think we will see fewer women attempting to do family and career simultaneously and more who think in terms of sequencing the two. Women are coming to realize that they can have it all, but, if they are to preserve healthy families not to mention their sanity, they cannot have it all at the same time.

Date published: 2/13/2005