Brian Structures and Sexual Orientation

Essay by PepsUniversity, Bachelor'sA-, April 2005

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Males and Females have the same structures within the brain, though particular structures differ in size, one structure, the Third Inistitial Nucleus of the Anterior Hypothalamus (INAH 3) is generally larger in the male population (LeVay, 1991) except in men who are homosexual. LeVay (1991) has shown that homosexual males have similar size structure of the INAH 3 to women. The similarity in INAH 3 size between homosexual men and heterosexual women maybe a cause of 'femininity' as Gorman (1994) stated that homosexuality is said to represent 'femininity' in males.

Homosexual men have an attraction toward other men, just as heterosexual women have an attraction toward men, with similar INAH 3 size do these 'female structures' within the male brain 'make' the individual a homosexual or do these structural differences occur secondary to homosexuality? Structural differences in the INAH 3 that are present at or before birth (possibly due to prenatal environment) should be able to be explained by biology (LeVay, 2003) while differences in structure size that occur secondary (after the individual recognises himself as homosexual) should be able to be explained through social experiences (Harrison, Everall and Catalan, 1994).

This paper will discuss homosexuality in reference to males only, unless stated otherwise, as studies into female homosexuality are few.

Biology shows differences in brain structures between men and women, size differences in structures, in particular the INAH. The INAH is found in the centre of the brain, below the hypothalamus and is composed of four regions INAH 1 through to 4, homosexual men have similar INAH 3 structural size to heterosexual women (Gorman, 1994) while homosexual women have similar structures to heterosexual men (LeVay, 1991). It has been suggested that sexual orientation may be 'hardwired' (Harrison et al, 1994) as some homosexual men say "that they...