Friedan uses this term in her discussion of functionalism, a school of thought within sociology and anthropology. Functionalists attempt to explain how individual roles work together to make a society operate. Friedan says that scholars in the functional school “began to mistake their own function as one of helping the individual ‘adjust’ to his ‘role’” in society (147). Functionalists would, for example, try to identify ways that women who felt incomplete as housewives could “adjust” their thoughts and feelings to align with the role society prescribed for them.

This phrase is a way to express the idea that in the nature versus nurture debate, nature wins; an individual’s biology determines their life course. As it relates to gender roles, the phrase signals the belief among some theorists Friedan discusses—Freud, most prominently—that women’s anatomy prescribes them the role of homebound mother. Friedan writes that the Freudian expression of this theory is that “the primitive instincts of the body determine[] adult personality“ (158). While most people classify Margaret Mead’s research as evidence that anatomy is not destiny because of its revelation that different cultures have different gender roles, Friedan sees evidence of the “anatomy is destiny” mindset in Mead’s insistence that women take pride in their childbirth abilities.