Is Sexual Orientation Innate?

From The Huffington Post:

A central tenet of modern neuroscience is that for every difference in behavior, whether between groups of people or within an individual person over time, there must be some corresponding differences in the structure or function of the brain. Accordingly, the brains of homosexuals somehow must be different from the brains of heterosexuals. Whether those differences were present at birth or acquired later in life is an important question, because if the differences are innate, then the attitudes of many people toward homosexuals could change.

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Many homosexuals believe that they were different from an early age and that they did not make a conscious choice to be homosexual. While this may be true, these are anecdotes, which are not convincing to science. However, research studies have shown several interesting differences between homosexuals and heterosexuals. (The following findings pertain to the averages of groups and thus will not necessarily be true of each individual person in a group.)

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With that said, there are other differences between homosexuals and heterosexuals that do not appear to be acquired and thus do appear to offer strong evidence of innate differences between the two groups (again, think group averages, not individual people):

• Homosexual males typically begin puberty earlier than heterosexual males.
• The chance of a male being homosexual goes up by about one third for each older brother he has.
• Homosexual males often have more aunts than uncles on their mother's side of the family.
• Homosexual males and females are both more likely to be left-handed than are heterosexual males and females.
• Homosexual males have penises that are larger, on average, than those of heterosexual males.
• Most boys who later identify as gay show preferences for girl-typical toys from a very early age.
• Certain characteristics of the inner ear are different between homosexual and heterosexual females.
• Certain characteristics of the auditory brain are different in both homosexual females and males...