I read the second edition of 1992. It includes 48 additional pages to the 1985 original: a preface; a new chapter on brain anatomy concerning sex differences and homosexuality; an afterword. The author explains that the book is imcomplete in so far as it does NOT include the topics women and depression, mothering instincts and transsexuality.
Instead she tackles most of all the questions of wether men are really smarter, genes and gender, hormonal hurricanes (menstruation, menopause, female behavior) and how women are put in their evolutionary place (by patriarchy).
The central theme is wether there is any scientific merit to the popular perceptions of the myriad sex differences. Anne Fausto-Sterling exposes various past sexist theories by patriarchal scientists, which the latter dropped as soon as they found out that on a closer, updated look, they would actually FAVOR women. Only to be replaced by new misogynous theories. The entire field of sociobiology is unmasked as an illusion.
I would like to mention though that races among humans are yet another illusion, as she uses this term all too often according to the times she was writing in.
You may be interested in the more elaborate complementing Mismeasure of Women: Why Women Are Not the Better Sex, the Inferior Sex, or the Opposite Sex. Also of interest are The Meanings of Sex Difference in the Middle Ages: Medicine, Science, and Culture (Cambridge Studies in the History of Medicine) and Nature's Body: Gender In The Making Of Modern Science.
PS: On societies with fathers doing a bulk of the child care read for example Intimate Fathers: The Nature and Context of Aka Pygmy Paternal Infant Care, for current lack of knowledge about a book of a (lost?) South American people, in which fathers do/did even more of the child care.