Prenatal Influences on Human Sexual Orientation: Expectations versus Data.

Area of Science:

• Neuroendocrinology
• Developmental Psychology
• Human Sexuality

Background:

• Sexual differentiation in vertebrates is organized by androgens, primarily testosterone.
• Prenatal androgen exposure is hypothesized to influence human sexual orientation development.
• Retrospective markers like digit ratio and otoacoustic emissions suggest prenatal androgen levels.

Purpose of the Study:

• To investigate the role of prenatal androgen exposure in human sexual orientation.
• To examine differences in prenatal androgen markers between heterosexual and homosexual individuals.
• To challenge popular notions regarding the fluidity and masculinization of sexual orientation.

Main Methods:

• Utilized retrospective markers of prenatal androgen exposure: digit ratios (2D:4D) and otoacoustic emissions.
• Compared these markers between groups of heterosexual women, lesbians, heterosexual men, and gay men.
• Analyzed sibling sex ratio as an additional marker for prenatal androgen exposure in men.

Main Results:

• Lesbians, on average, exhibited greater prenatal androgen exposure than heterosexual women.
• No significant difference in average prenatal androgen exposure was found between gay and heterosexual men.
• Gay men showed a higher proportion of older brothers compared to heterosexual men.

Conclusions:

• Prenatal androgen exposure plays a significant role in shaping sexual orientation in women.
• Sexual orientation in men may be influenced by androgen response rather than exposure levels.
• Findings challenge the concepts of sexual orientation fluidity in women and under-masculinization in gay men.