Pediatric Neuroendocrinology

Editor(s): Loche S. (Cagliari) 
Cappa M. (Rome) 
Ghizzoni L. (Turin) 
Maghnie M. (Genova) 
Savage M.O. (London) 
Table of Contents
Vol. 17, No. , 2010
Section title: Paper
Loche S, Cappa M, Ghizzoni L, Maghnie M, Savage MO (eds): Pediatric Neuroendocrinology. Endocr Dev. Basel, Karger, 2010, vol 17, pp 22–35

Sexual Hormones and the Brain: An Essential Alliance for Sexual Identity and Sexual Orientation

Garcia-Falgueras A. · Swaab D.F.
Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands

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The fetal brain develops during the intrauterine period in the male direction through a direct action of testosterone on the developing nerve cells, or in the female direction through the absence of this hormone surge. In this way, our gender identity (the conviction of belonging to the male or female gender) and sexual orientation are programmed or organized into our brain structures when we are still in the womb. However, since sexual differentiation of the genitals takes place in the first two months of pregnancy and sexual differentiation of the brain starts in the second half of pregnancy, these two processes can be influenced independently, which may result in extreme cases in trans-sexuality. This also means that in the event of ambiguous sex at birth, the degree of masculinization of the genitals may not reflect the degree of masculinization of the brain. There is no indication that social environment after birth has an effect on gender identity or sexual orientation.

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