Read an Excerpt

You’re finally getting to know the new neighbors. They moved in a week ago, but you’ve had no chance to chat, which is surely why you didn’t notice sooner that the woman is pregnant. Very pregnant, by the looks of it.
     “How wonderful!” you croon over your common fence. “Do you know if you’re having a boy or girl?”
     Why is this always the first question we ask when learning about a new baby? The answer is simple: because sex is a big deal. Not just the act of it, but the fact of it. Of all the characteristics a child brings into the world, being male or female still has the greatest impact — on future relationships, personality, skills, career, hobbies, health, and even the kind of parent the child is likely to become. That’s why 68 percent of expectant parents learn the sex of their child before birth and why you know your neighbor is naive to answer, “We really don’t care, as long as the baby is healthy!”
     Most American parents hope to have at least one child of each sex. We enjoy the differences between them, even as we worry about their consequences. Will this little boy, now so active and exuberantly affectionate, settle down enough to begin school? Will he form meaningful relationships with his friends and teachers? Will he still express his feelings or, for that matter, communicate with us at all when he grows up?
      For parents of girls, the fears run in the opposite direction. Here she is, so confident and full of life. Will she still dig for worms and wonder about the planets when she’s in middle school? Will she be assertive enough when she lands her first job out of college? Will it be any easier for her generation to juggle career and family when she grows up?

Boys and girls are different. This fact, obvious to every previous generation, comes as a bewildering revelation to many parents today. Raised in an era of equal rights, we assume — or at least hope — that differences between the sexes are made, not inborn. We mingle comfortably with members of the opposite sex, harangue as easily about sports as cooking, and cheerfully compete in the workplace — all the while pretending the two sexes are more or less the same.
     Until we have kids of our own, at which point the differences are impossible to ignore.
     Like many parents, I could cite endless examples of the differences between our daughter and two sons: Julia loves shopping, while Sam and Toby can barely be persuaded to try on jeans at the mall. Then there was the evening not so long ago that Julia spent drawing pictures of fairies while Sam and Toby raced around the house having a light-saber battle. Even as a young toddler, Julia would lay all our kitchen towels on the floor and then put a stuffed animal on each one for “nappy time.” The only thing that absorbed Sam and Toby as much at that age was seeing how many objects they could jam inside a VCR.
     Also, like other parents today, I feel compelled to excuse this gender-typical play with the obligatory “We certainly didn’t encourage Julia to play only with girl toys and Sam and Toby to play only with boy toys.” On the contrary, many of our kids’ building toys — the wooden blocks, Duplos, and Lincoln Logs — were originally purchased for Julia, our oldest child. I try to make a point of praising the boys’ nurturing behavior — like when Sam hugs Toby or cuddles his pet gerbil — and never stand in the way of their attempts to help me cook.
     Of course, parents are never truly neutral about gender. Regardless of which toys or clothes we buy them, we cannot help but react in different ways to our sons and daughters — if only because of our own long experience of “male” and “female.” But still, I had thought our kids would be different. As a neuroscientist and Martha Stewart dropout, I am hardly the typical female role model. My husband, also a scientist, fits the male type in many ways (he can fix almost anything around the house — as long as it doesn’t interfere with Monday Night Football) but is kinder and gentler than many of the women I know.
     And yet, there they are: Julia quietly makes paper flowers or sets up her Playmobil house while Sammy launches cars off his Hot Wheels track or begs me to pitch Wiffle balls to him outside. Even little Toby, with his clear, high-pitched voice, started steering the boy course early, judging from his toddler fascination with trucks, airplanes, balls, and any kind of electrical appliance.

Yes, boys and girls are different. They have different interests, activity levels, sensory thresholds, physical strengths, emotional reactions, relational styles, attention spans, and intellectual aptitudes. The differences are not huge and, in many cases, are far smaller than the gaps that separate adult men and women. Little boys still cry, little girls kick and shove. But boy-girl differences do add up, leading to some of the more alarming statistics that shape the way we think about raising our children.
     Here’s a stark one: Boys are at greater risk than girls for most of the major learning and developmental disorders — as much as four times more likely to suffer from autism, attention deficit disorder, and dyslexia. Girls, for their part, are at least twice as likely as boys to suffer from depression, anxiety, and eating disorders. Boys are 73 percent more likely to die in accidents and more than twice as likely to be the victims of violent crimes (other than sexual assault). Girls are twice as likely as boys to attempt suicide, but boys are three times likelier to succeed at it.
     On the academic side, girls of all ages get better grades than boys. Women now constitute the majority of U.S. college students — a startling 57 percent. And yet males continue to score some twenty-five points higher on the SAT exam and outnumber females four to one in college engineering degrees. In spite of their educational gains, women earn less than eighty cents for every dollar earned by men.
     Sex  matters. As much as we may strive to treat them equally, boys and girls have different strengths and weaknesses and face very different challenges while growing up. Boys are more vulnerable early in life: they mature more slowly, get sick more often, and are less likely to have mastered the language, self-control, and fine motor skills necessary for a successful start in school. In recent years, as academic expectations have intensified, boys’ slower start is stretching into a significant handicap even into the middle-school and high-school years, where they trail girls in graduation rates, academic performance, and extracurricular leadership positions.
     Girls pull through the early years more easily than boys, hitting their vulnerable phase around puberty, when their confidence slips, their math and science interests wane, and young womanhood comes to be defined by beauty and submissiveness. Then, after girls navigate the minefield of adolescence, they face even greater challenges out in the real world, where they struggle with the contradictions of ambition and femininity and the conflicting values of the workplace and child rearing.
     These differences between the sexes have real consequences and create enormous challenges for parents. How can we support both our sons and daughters, protect them, and still treat them fairly when their needs are so very different?
     I study the brain and believe we can’t even hope to tackle these issues until we know where the differences come from. What is going on inside boys’ and girls’ heads that triggers such different interests, emotional reactions, and mental abilities? Are male and female brains fundamentally different from each other? Are boys and girls wired differently from birth?