A thorough critique of over 300 research studies (all that were done before 2000, major ones after) on the effects of sex hormones in masculinizing/feminizing the brain of the unborn child, analyzing their methodology, definitions and findings. Very clear and straightforward writing style, and fair in its approach. The author also interviewed over 20 of the major researchers in this field to understand and clarify their findings and views. The upshot is that, although the idea that male and fema

A thorough critique of over 300 research studies (all that were done before 2000, major ones after) on the effects of sex hormones in masculinizing/feminizing the brain of the unborn child, analyzing their methodology, definitions and findings. Very clear and straightforward writing style, and fair in its approach. The author also interviewed over 20 of the major researchers in this field to understand and clarify their findings and views. The upshot is that, although the idea that male and female brains are differentiated before birth by exposure to sex hormones has become almost a given, the data from the studies do not back up this claim as the major source of sex differences.



I will give two examples of her findings. One problem with the studies is that the definitions of what constitutes masculine and feminine behavior have changed greatly, especially after 1980, so that behaviors considered evidence of masculinization (such as masturbation, arousal by any means other than touch, multiple partners, etc, - a long list) in the early studies are since the 1980s considered gender neutral, but the conclusions of the earlier studies based on the older definitions are still cited as if the definitions have remained the same throughout. Most of the researchers she spoke with felt that what was masculine and feminine was so obvious that a commonsense understanding was good enough, although this commonsense understanding has changed radically since WWII. A second issue is that definitions of terms such as homosexual are inconsistent in a way that makes findings from various studies in fact contradict each other though they seem superficially to agree. Is a lesbian the counterpart of gay men because both are attracted to people of the same sex, or a counterpart of straight men in that they are both attracted to women? How these pairings line up in a particular study makes a difference in what behaviors are considered feminized or masculinized. Further, the author also points out that most studies that find negative results are not published, which is typical for negative results but also misleading, just as it is in drug trials for example. The author is an extremely scrupulous and detail-oriented scholar, but the book is not at all tedious if you are interested in whether and how much the human brain is masculinized or feminized by prenatal hormone exposure.



This book was referred to in Cordelia Fine's book Testosterone Rex.