The Science of Sexual Orientation

(from psychologicalscience.org)
(from psychologicalscience.org)

Happy New Year!

I figure I’ll kick things off with something a little different than my usual science of addiction posts.

My new job deals with supporting LGBT rights in the developing world and there’s a lot of work be done! In fact, as of June 2016, 77 countries or territories criminalize homosexuality and 13 countries or territories penalize homosexual behavior by death. But why is this? Why is someone who is attracted to and has sex with someone of the same sex so controversial in so much of the world? Well..I’m not about to begin to answer that question because I’ll be writing all week (hint, hint: religion is a huge factor).

Instead, I’ll present some of the key findings from a relatively new (April 2016) review article about the science of sexual orientation by JM Bailey and colleagues in the journal Psychological Science in the Public Interest. This is by far one of the most comprehensive and most even handed review articles written on the subject. The authors take an extremely academic approach because let’s face, the science surrounding sexual orientation has been used and abused by both pro- and anti- gay rights folks. (note: this article does not really discuss with transgenderism or gender identity issues)

This article is too long to go into all the details so instead I’m just going to present the main highlights that I prepared for a research report a few months back. Enjoy!

Download the article here. It’s Open Access!

jm-bailey-et-al-2016

Brief Summary:

Political controversies pertaining to the acceptance of non-heterosexual (lesbian, gay, bisexual) orientation often overlap with controversies surrounding the science of sexual orientation. In an attempt to clarify the erroneous use of scientific information from both sides of the debate, this article 1) provides a comprehensive review of the current science of sexual orientation, and 2) considers the relevance of scientific findings to political discussions on sexual orientation.

Top Takeaways from the Review:

  • The scientific evidence strongly supports non-social versus social causes of sexual orientation.
  • The science of sexual orientation is often poorly used in political debates but scientific evidence can be relevant to specific, limited number of issues that may have political consequences.
(wikimedia.org)
(wikimedia.org)

The scientific evidence strongly supports non-social versus social causes of sexual orientation (nature vs nurture).

Prevalence of non-heterosexual orientation (analysis of 9 large studies): 5% of U.S. adults.

Summary of the major, scientifically well-founded findings supporting non-social causes:

  • Gender non-conformity during childhood (before the onset of sexual attraction) strongly correlates with non-heterosexuality as an adult.
  • Occurrence of same-sex behavior has been documented in hundreds of species and regular occurrence of such behavior in a few species (mostly primates, sheep).
  • Reported differences in the structure of a specific brain region (SDN-POA) between heterosexual and homosexual men.
  • Hormone-induced changes in the SDN-POA during development in animal studies and subsequent altered adult sexual behavior (the organizational hypothesis).
  • Reports of males reared as females but who exhibit heterosexual attractions as adults.
  • Twin studies suggest only moderate genetic/heritable influence on sexual orientation.
  • Several reports identify a region on the X chromosome associated with homosexuality.
  • The most consistent finding is that homosexual men tend to have a greater number of biological older brothers than heterosexual men. (fraternal-birth-order effect)

The science of sexual orientation is often poorly used in political debates, but scientific evidence can be relevant to a specific, limited number of issues that may have political consequences.

The question of whether sexual orientation is a “choice” is logically and semantically confusing and cannot be scientifically proven. It should not be included in political discussions.

Examples of scientifically reasonable questions include:

  • Is sexual orientation determined by non-social (genetic/hormonal/etc.) or social causes? (nature vs nurture)
  • Is sexual orientation primarily determined by genetics or environment?

Specific cases in which scientific evidence can be used to inform political decisions:

  • The belief that homosexual people recruit others to homosexuality (recruitment hypothesis). This type of belief was espoused by by President Museveni of Uganda in 2014 and was used to justify Uganda’s notorious anti-homosexuality bill (since repealed).
    • No studies exist that provide any type of evidence in support of this hypothesis.
  • Proponents of conversion/reparative “therapies” argue that sexual orientation can be changed through conditioning and reinforcement.  Gov. and VP-elect Mike Pence  allegedly supported these types of bogus “therapies” in Indiana.
    • Studies reporting successful “conversion” suffer from methodological errors such as selection bias and/or unreliable self-report data and are therefore scientifically unfounded.
    • No evidence exists that a person’s sexual orientation can be changed at will.

 

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The NIH Announces a Commitment to Research on LGBT Health

lgbt-med

Every person has a right to live a healthy life. One part of that vision is equal access to health care for all. But unsurprisingly, not everyone have the same ability to receive health care due to things like socioeconomic status, race, gender, or even sexual orientation. Indeed, LGBT people often have less access to health care than their non-LGBT counterparts, most often due to discrimination and stigma [1].

The Director of the National Institute on Minority Health and Health Disparities, part of the National Institutes of Health (NIH), announced “the formal designation of sexual and gender minorities (SGMs) as a health disparity population for NIH research.” Read the full announcement here.

What does this mean? That the NIH is officially recognizing that LGBT people have less access to health care and that improved research on LGBT-specific (defined here broadly as sexual and gender minorities) health issues is essential to improved health care.

The long-overdue announcement was supported by an important report released by the non-partisan National Academies of Science (NAS) in 2011. The report identified gaps in the research on the health of LGBT persons and made recommendations for improving this research that could benefit not just LGBT people, but the health care system overall.

LGBT individuals have unique health challenges that many doctors do not understand or address. For example, certain types of cancer seem to be more prevalent among gay men compared to straight men, which means different cancer screenings would be important for gay men [2].

The new designation by NIMHD will hopefully increase research and knowledge about the health challenges of LGBT people and will hopefully result in improved health care for all people, regardless of sexual orientation, gender identity, or gender expression.

Selected References

  1. Hatzenbuehler ML, Bellatorre A, Lee Y, Finch BK, Muennig P, Fiscella K. Structural stigma and all-cause mortality in sexual minority populations. Social science & medicine. 2014;103:33-41. doi: 10.1016/j.socscimed.2013.06.005.
  2. Quinn GP, Sanchez JA, Sutton SK, Vadaparampil ST, Nguyen GT, Green BL, et al. Cancer and lesbian, gay, bisexual, transgender/transsexual, and queer/questioning (LGBTQ) populations. CA: a cancer journal for clinicians. 2015;65(5):384-400. doi: 10.3322/caac.21288.