Chapter II. A woman’s intelligence and/or beauty
Girl or boy, nature or nurture
Neurologists only know one force that is capable of shrinking or stimulating, killing or growing the neuron net: sex hormones. Prior to birth, the fetus’ brain is awash in sex hormones. Ethics prevent scientists from carrying out experiments to determine how the brain can change in response to hormonal changes. But nature has no such compunctions. Girls with a rare birth defect called CAH, which made them churn out high levels of the male hormone testosterone as fetuses, score better than average female on spatial tests. (By the way, the extra testosterone exposure also changes their genitals into masculine.) As girls, they prefer cars and trucks and other toys that boys usually grab.
A similar effect is caused by the use of the hormone DES to prevent miscarriages. It causes female fetuses to produce testosterone intensively. Upon birth DES girls are more like boys in their orientation than like ‘normal’ girls. Conversely, boys with insufficient testosterone or excessive estrogen (the female hormone) are more successful in language disciplines than their normal brethren.
In the opinion of the psychologist Doreen Kimura of the University of Western Ontario, "hormonal effects appear to extend to all know behaviors in which males and females differ." In this connection, the question is often discussed: are these differences programmed automatically from the moment of the child’s birth, or do they emerge later in the process of growth (nurture)?
The answer given is this: the feminized boys and the CAH girls (minds like boys) are not physically normal. Parents usually understand this and raise the children based on their understanding. This is why it is hard to say which ultimately has the greater influence: original hormones or subsequent upbringing. Only DES girls are pure hormone products. On the whole, both matter: nature and nurture. The brain determines behavior; behavior has influence on brain structure.
On Love, Family, and the State
(Philosophical-sociological Essay)