“It’s worth remembering just how much society can change in a relatively short period of time. Precedents are still being set. Could a society in which males and females hold equal places ever exist? Ironically, perhaps it is not biology that is the implacably resistant counterforce, but our culturally attuned minds.” 

Fine lays out her fundamental argument: It is cultural habit, not innate biological difference, that keeps sexism alive. Society is malleable; the difficulty lies in persuading people that this is so.

“Suppose a researcher were to tap you on the shoulder and ask you to write down what, according to cultural lore, males and females are like. Would you stare at the researcher blankly and exclaim, ‘But what can you mean? Every person is a unique, multifaceted, sometimes even contradictory individual [...] and it would be pointless and meaningless to attempt to pigeonhole such rich complexity and variability into two crude stereotypes?’ No. you’d pick up your pencil and start writing.” 

As is repeatedly demonstrated over the course of the book, our more complex ideas about personhood sit at odds with our intense cultural training. Whether or not we consciously believe in them, gender stereotypes are embedded deeply in our psyches. It’s not easy to escape them.

“[T]he boundary of the self-concept is permeable to other people’s conceptions of you (or, somewhat more accurately, your perception of their perception of you).” 

Popular notions of an unchanging self are at odds with what researchers can observe in testing conditions. The ways that we think about ourselves—and even our capacities—are astonishingly alterable by other people’s perceptions. And those perceptions are heavily conditioned by gender expectations.