Gay and straight people show neurological differences

Question: Are people born gay?
Position1 of 4›: Yes, people are born gay
Argument‹4 of 6›: Gay and straight people show neurological differences

Gay people have a different neurological structure to their heterosexual peers.

The argument

In 1991 the British-American neuroscientist Simon LeVay carried out postmortem examinations of brain tissue from three groups: women, men assumed to have been homosexual, and men assumed to have been heterosexual. His attention fell on four cell groups known collectively as INAH3, which are associated with the regulation of male-typical sexual behaviour. LeVay reported that these cell groups were substantially larger in the heterosexual men than in either the women or the men presumed to have been homosexual, in whom they were much smaller. The finding did not stand alone. A 2008 study by the Stockholm Brain group reported the corresponding pattern from the other direction: lesbian women and straight men were found to share the larger INAH3 groupings. Taken together, the two results describe a structural difference that sorts by sexual orientation rather than by sex alone. The inference proponents draw turns on what kind of trait brain structure is. Gross anatomical features of this sort are laid down developmentally; they are not the kind of thing a person acquires through choice, upbringing or later experience in the way a preference or a habit might be. If orientation were purely a matter of what someone decides or learns, there would be no reason to expect it to leave a consistent signature in the size of a specific cell group — still less for that signature to appear independently in separate studies conducted seventeen years apart in different research settings. That it does appear is taken to show that orientation is grounded in innate neurological organisation rather than in subsequent choice or circumstance. The brain differences are treated as evidence of something present from the start, of which adult orientation is the expression rather than the cause. On this argument, people are born gay.

Context

Homosexual and heterosexuals do not have the same neurological structure.

Premises

[P1]LeVay's postmortem research found that the INAH3 cell groups regulating male-typical sexual behaviour were substantially smaller in homosexual men and women than in heterosexual men. [P2] A 2008 Stockholm Brain study corroborated this by finding that lesbian women and straight men share similarly larger INAH3 groupings. [P3] Such consistent neuroanatomical differences between gay and straight people indicate an innate biological basis for sexual orientation. [C] Therefore, people are born gay.

Counter-arguments

This does not mean that we are born gay. Our brain is not fully developed at birth. Therefore, the discovery of neurological differences between gay and straight people does not mean that we are born gay. LaVey himself even admitted in 1994 that just because homosexuals and heterosexuals have different neurological differences, it does not necessarily indicate that they were born this way. He also admitted that the brains he studied had died from AIDS. He could not rule out that the neurological discrepancies were not caused by the disease. Additionally, neuroscience is an area in which we still know very little. The correlation between regions of the brain and behavioural traits has not been proven beyond doubt.

Rejecting the premises

[Rejecting P2] Neurological structure does not emerge before birth.