For most women, it isn’t hard to come up with some basic generalizations about the differences between women and men. Females go to the bathroom in pairs; males go decidedly alone. Women take longer to reach orgasm; men don’t like to cuddle. Moms are nurturers; dads are protectors.

But are these behaviors innate or learned, nature or nurture? Most biologists are at an impasse, conceding that sex specific behaviors are due, in varying parts, to a combination of genetics and culture. However, in The Female Brain, Loann Brizendine, a neuropsychiatrist at the University of California, San Francisco, tells a story in which our actions are heavily influenced by our hormones and brain structure and thus, our DNA.

Describing the intricacies of neuroendicrinology could be daunting, but Dr. Brizendine does it in an easy-to-digest manner. As the founder of the Women’s and Teen Girls’ Mood and Hormone Clinic, she is able to blend scientific and clinical research, anecdotal stories, and personal observations with a conversational, casual tone (estrogen is “an aggressive seductress” while testosterone “has no time for cuddling.”)

Seven chapters take us from womb to womanhood. In the uterus we learn that “every brain begins as a female brain” and only becomes male when testosterone shrinks the hearing and communication centers and makes the sex-processing center twice as large as that of females.

We also learn that from birth, girls spend more time gazing at their mothers faces and are more attuned to nonverbal cues than are boys. On the playground, girls begin sentences with words like “let’s,” inviting social connections and relationships, while boys are more likely to smash the blockhouse the group of girls just built.

According to the book, these traits can be explained by looking at brain structure and function. Women’s communication centers are bigger, and we can respond better to what others need. This goes back to the Stone Age, where survival meant being able to read an infant’s face and form social bonds. Preserving peace is something that comes naturally: “If you’re a girl, you’ve been programmed to make sure you keep social harmony.”