Boys are better in math, girls are more empathetic – there’s something almost alluring about the idea that our brains are wired differently. But in her new book, Pink Brain, Blue Brain, author and neuroscientist Lise Eliot synthesizes decades of research on the topic and concludes that both sexes – boys in particular – are suffering under our assumptions about their nature.

Our X and Y chromosomes really do seem to point us in different directions. From the beginning, girls are more resilient and faster to develop than boys. They get a head start in language and fine motor skills. By four months, girls make more eye contact (not surprisingly, women are found later to be more skilled at reading emotion). Boys are more fussy as babies and vulnerable throughout childhood. Their motor skills are on par with girls’, though, and they tend to do more jumping, running, and general stunt work than their female counterparts.

But according to Eliot, the biological differences between us are actually very small. Average skill levels vary slightly, but it’s nothing close to how much the sexes differ in height, for example. When it comes to abilities and personality traits, there is way more variation within each sex than there is between the sexes. And the overlap is huge, meaning lots of boys are more verbal than girls and lots of girls are more active than boys.

So how do we go from slight biological variations to a clear gender divide? It starts when our babies come home from the hospital to their sports-themed or doll-inhabited rooms. Despite their best intentions, moms and dads treat their little ones differently, with boys tending to get tossed in the air and rough-housed more and girls tending to be described by their parents as softer and more delicate. One study in Eliot’s book asked moms to judge how steep an incline their eleven-month-old could crawl down and showed that moms doubted the skill and courage of the girls and made the ramp steeper for the boys, even though both sexes were equally capable. Studies also show that parents (dads in particular) are less supportive when, for example, their boy cuddles a baby doll, than when he wields a lightsaber.

Our biases are hurting the boys in particular, says Eliot. They are more likely to be held back from kindergarten, or labeled with ADHD and learning disorders. We expect them to be slower and less focused, instead of challenging them and adapting our teaching methods. She gives a lot of suggestions to help boost boys’ communication and fine motor skills (two areas that have a big impact on school performance). For example, teach boys to type early; read non-fiction; and encourage cutting, stamping, and painting. Boys need more chatting and soothing and less “toughening up” – they require just as much help, if not more, understanding their feelings.

Girls have been on the rise for a while now, but math and science are still dominated by boys, partly because we assume that they have a natural advantage. In reality, boys only excel in visuospacial skill (the ability to mentally rotate an object), and girls actually tend to get better grades in both math and science. But the ladies fall off once they hit adolescence, which Eliot argues is because they get the message that hard-core math is not their turf and they lose confidence. Women are well represented in medicine (which has a human, helping side), but we still don’t have very many female aerospace engineers or computer scientists. Give Legos and Lincoln Logs to girls, says Eliot. They need balls and paper airplanes, jigsaw puzzles and tool sets. Get them onto the computer for some fast-paced targeting games to practice spatial reckoning and healthy competition.

There is no gene for garbage truck obsessions or tiaras and tutus, but if we only follow our children’s lead and never challenge them to step out of their comfort zones, guess what will happen? Our brains are remarkably “plastic,” meaning that they grow and strengthen based on our experiences. So imagine that your boy needs a lot of emotional support and that your girl might grow up to be a wacky math professor. “Whatever you do is what your brain will be ‘wired’ for,” says Eliot. “So anytime we see an obvious difference between men and women, or boys and girls, ask yourself: how did they spend their time over the past thirty years to make their brains so good – or bad – at certain skills?”