Lecture Notes: The Science of Homosexuality

Overview

• 2-6% of people self-identify with predominantly homosexual attractions.
• Science investigates whether being gay is genetic.

Genetic Studies

• 1990s Human Genome Project Studies:
  • Higher number of homosexual relatives in gay men.
  • Gay siblings show similar X chromosome linkages.
• Recent Studies:
  • Study of 409 gay siblings shows linkages in X chromosome region XQ28 and chromosome 8.
  • 2014 analysis over 50 years shows gay men likely have gay brothers, lesbians likely to have lesbian sisters.

Genetic Paradox

• Gay individuals have 80% fewer children, raising the question of gene survival.
• UCLA Epigenetics Study:
  • Everyone may have a 'gay gene', expressed via methylation.
  • Study on twins suggests methylation patterns linked to sexual orientation (70% prediction accuracy).
  • Controversy exists due to small sample size.

Genetic and Molecular Regulation

• No specific 'gay gene' found.
• Genetics and molecular levels strongly influence sexual orientation.
• Male pregnancies may increase homosexuality odds in subsequent sons by 33%.
• Meta-analysis:
  • Homosexual men statistically have more older brothers.
  • High prenatal testosterone exposure linked to higher rates of not being straight.

Evolutionary Hypotheses

• Gay Uncle Hypothesis:
  • Non-reproductive gay family members increase gene prevalence by supporting relatives' offspring.
• Attraction Coding Hypothesis:
  • Genes for homosexuality might enhance opposite-sex attraction in female relatives, leading to more offspring.

Social and Historical Context

• Historically, science viewed homosexuals negatively.
• Concerns exist over potential misuse of genetic research against the LGBTQ2S community.
• Most studies focus on gay men, neglecting other groups.
• Continued research can combat homophobia by proving that being gay is not a choice.

Future Implications

• Discussion on whether it's possible to genetically eliminate homosexuality.
• Impact of continued research on social and legal perceptions of homosexuality.

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