Thus for example a female brain has more connections between the two sides of the brain, and is better able in general to articulate and to express emotion verbally. In return the male brain is more specialised in function and thus often has better perceptual and motor skills. In autopsies of transsexuals some brain patterning has been found to follow that of the adopted sex. Similarly twelve transvestites and transsexuals given an Oestrogen Provocation Test some years ago resulted in seven showing a female response to injected oestrogen, and one an intermediate response, while a control sample of twelve non-transgendered males produced eleven male responses. The impetus for this patterning appears to come some six or so weeks after conception.
All foetuses produce male and female precursor hormones.
Where the ratio falls too far the greater specialisation of the male brain does not happen, or only partially occurs. The result may be one or more of an intersex condition of body, sexuality, or brain patterning depending on the exact stage of development reached when the problem occurs and the length of time it persists. A parallel to this is found in the Androgen Insensitivity Syndrome . Around 1 in 40,000 males do not respond at all to male hormone. The result is physically and mentally a woman but without ovaries or vagina.