Editing Heterosexuality (section)

==== Prenatal hormones ====
{{Main|Prenatal hormones and sexual orientation|Neuroscience and sexual orientation}}
{{multiple image
 | align = vertical
 | width1 = 168
 | image1 = 2AM9.png
 | caption1 = Structure of the [[androgen receptor]] (rainbow cartoon) complexed with testosterone (white sticks).<ref name="pmid16641486">{{PDB|2AM9}}; {{cite journal |vauthors=Pereira de Jésus-Tran K, Côté PL, Cantin L, Blanchet J, Labrie F, Breton R | title = Comparison of crystal structures of human androgen receptor ligand-binding domain complexed with various agonists reveals molecular determinants responsible for binding affinity | journal = Protein Sci. | volume = 15 | issue = 5 | pages = 987–99 | date =May 2006 | pmid = 16641486 | pmc = 2242507 | doi = 10.1110/ps.051905906 }}</ref>
 | width2 = 185
 | image2 = Testosterone-from-xtal-3D-balls.png
 | caption2 = [[Testosterone]] contributes to the masculinization of the brain
 | width3 = 200
 | image3 = Oestradiol-3D-balls.png
 | caption3 = [[Estradiol]] also stimulates the [[androgen receptor]]s.
 }}

The neurobiology of the masculinization of the brain is fairly well understood. [[Estradiol]] and [[testosterone]], which is catalyzed by the enzyme [[5α-reductase]] into [[dihydrotestosterone]], act upon [[androgen receptor]]s in the brain to masculinize it. If there are few androgen receptors (people with [[androgen insensitivity syndrome]]) or too much androgen (females with [[congenital adrenal hyperplasia]]), there can be physical and psychological effects.<ref>Vilain, E. (2000). Genetics of Sexual Development. Annual Review of Sex Research, 11:1–25</ref> It has been suggested that both male and female heterosexuality are the results of this process.<ref>Wilson, G. and Rahman, Q., (2005). Born Gay. Chapter 5. London: Peter Owen Publishers</ref> In these studies heterosexuality in females is linked to a lower amount of masculinization than is found in lesbian females, though when dealing with male heterosexuality there are results supporting both higher and lower degrees of masculinization than homosexual males.