One of the most astounding things about the brain is that it contains our entire mind. All of our memories, thoughts, feelings, and preferences are contained within this mass of flesh that is, well, just meat. Given that we are our brains, it follows that our gender and sexuality, as part of our identities, are necessarily determined by some characteristics of our brains. To properly examine the LGBTQIA+ experience, we’ll take a look at some of the neurological and psychological factors underlying the different genders and sexualities we see.

However, before we begin our discussion of these topics, it is critical to understand the difference between sex, gender, and sexuality. In particular, sex is based on biological characteristics, while gender is how a person identifies based on their own feelings. Further, neither has only two types, as seen by the presence of many intersexed and nonbinary individuals. We must also remind ourselves that different sexes, sexualities, and genders are human categorizations for certain physical characteristics and patterns of behavior that are not always consistent and do not always fit into boxes. There are many different physical characteristics, levels of attraction, and types of behavior that humans and other organisms can participate in. Conceptions about which of these correspond to which genders or which sexualities are arbitrary, and can often vary between individuals. Our strict categorization of sex, gender, and sexuality cannot possibly reflect the great physical, mental, and behavioral diversity and intricacy of the human species. An understanding that all of these characteristics are natural is a prerequisite to understanding the LGBTQIA+ experience.

An Evolutionary History

In the past, scientific literature on different sexualities and genders in the context of evolution has been vastly corrupted by the biases and skewed assumptions of scientists [1]. A question that these scientists often asked, and one that has consistently dehumanized LGBTQIA+ people, is how different genders and sexualities have evolved from the first organism with multiple sexes. Contained within this question are the assumptions that this common ancestor exhibited only different-sex behavior, from which same-sex behavior evolved, and that same-sex behavior is maladaptive and costly to reproductive success. In the past, scientists attempted to manufacture many reasons why it was adaptive or explain why it arose in so many species from the “ancestral” and “optimal” trait of different-sex behavior.

However, this approach to analyzing same-sex behavior’s evolutionary history contains a flawed assumption: that same-sex behavior is unnatural and its cost to fitness is high. In fact, the existence of a particular class of organisms called echinoderms suggests that multiple sexes evolved before the sensory equipment needed to differentiate between them [1]. Some of these organisms, including sea urchins, cannot determine the sex of an organism they are mating with, and therefore exhibit indiscriminate sexual behavior [2][3]. This does little to actively reduce fitness. If an organism engages in same-sex behavior, this in no way prevents it from engaging in different-sex behavior that leads to reproduction, and the cost of this is quite low. Additionally, traits that make organisms more likely to engage in mating behavior overall may happen to result in increased same-sex behavior as a byproduct and still be evolutionarily advantageous [4]. Consistent with this explanation, same-sex behavior has been found in more than 1500 species, and it continues to be identified in more every day [1]. Further, while reproductive fitness is important to consider in the context of evolutionary history, the real or perceived reproductive fitness of an LGBTQIA+ individual today is no one’s business but their own and should have no bearing on their value to society.

The idea that different-sex behavior was the baseline from which same-sex behavior evolved stems from cultural biases around what is natural and unnatural, which both insults the LGBTQIA+ community and hampers the progress of science (read more about how bias holds back science here). Regardless, it is becoming increasingly well-established that same-sex behavior has existed as long as sexual reproduction has existed. Indiscriminate sexual behavior was the baseline from which selectivity towards the same or opposite sex evolved. And indeed, a critical part of understanding the LGBTQIA+ experience is the realization that these orientations are as natural as heterosexuality.


Both sexual orientation and gender presentation are determined by our neural concepts of them, and many LGBTQIA+ individuals emphasize that they feel their genders and sexualities are innate and inborn. This suggests that they may exhibit concrete neural differences, and indeed, we see statistically significant differences in grey matter volume of certain brain areas between people of different genders and sexualities [5]. In particular, one region of the thalamus varies in size depending on the subject’s gender and sexuality, and it’s hypothesized that this brain region could be involved with linking different sensory stimuli with reward. Another region of the cerebral cortex, called the precentral gyrus, activates in response to viewing different kinds of sexual activity depending on the subject’s sexuality, regardless of the subject’s gender, suggesting that different brain areas may affect gender and sexuality [5]. If the regions affecting gender and sexuality are indeed independent, that would be very consistent with the large variety of sexualities and genders we see in humanity today.

In addition to the question of what neural differences exist between LGBTQIA+ individuals and heterosexual, cisgendered individuals, an important question is how these differences arise. One possible hypothesis to begin with would be to examine the effects of different levels of sex hormones on gender and sexuality. Congenital adrenal hyperplasia is a condition in which the adrenal glands become enlarged during prenatal development, and as a consequence release a comparatively large amount of androgens, or hormones that lead to the development of male sex characteristics [6]. Scientists observed that women with congenital adrenal hyperplasia during development display higher rates of bisexuality and homosexuality than people without it, suggesting that hormone levels during development can affect sexuality [6]. However, it is important to note that this effect is small and nondeterministic, and that even while congenital adrenal hyperplasia itself may be treated if desired, the bisexuality and homosexuality among these women does not interfere with quality of life, and does not need to be “cured”.

A second discovery of sexuality development begins with a trend observed among homosexual males is that they often have older brothers. In fact, a scientist named Dr. Ray Blanchard found that each additional older brother correlates with a 33% increase in likelihood of homosexuality [7]. His hypothesis to explain this was the maternal immune hypothesis, which suggests that as mothers bear more male offspring, they develop an immune response that targets H-Y antigens, which are likely involved in the development of sex-typical traits, and may affect sexual differentiation in the brain [7]. To explore the biological correlates of this, scientists at Michigan State University sampled blood from women and found that women who had borne more male sons had higher levels of antibodies that targeted a protein called neuroligin 4 (NLGN4Y), which is on the Y chromosome and is important in brain prenatal development [8]. Future research will no doubt shed further light on the intricate molecular mechanisms behind the trends we observe outside the womb.


Society as it is today imposes a great deal of trauma on LGBTQIA+ individuals, and this translates into significant rates of mental health disorders among our community. In general, minority groups experience an extra mental burden termed “minority stress,” as society teaches them to perceive their minority identity as a burden to themselves and those around them [9]. Studies suggest that this is a major factor leading to depression and suicidal thoughts among LGBTQIA+ youth [9]. Further, minority stress seems to be far worse in countries where people are less accepting of LGBTQIA+ identities, as well as for particularly marginalized identities in the community, such as transgendered individuals; around half of the individuals in either of these categories suffer from depression, and intersectionalities between transgenderism and an unaccepting culture need to be further explored [10][11]. The effects of minority stress combined with the bullying that many members of the community experience leads to a rate of suicide among LGBTQIA+ people six times that of the population [12]. Among transgender or nonbinary individuals, the rates are around 40% [13].

It is important to note that unlike other identities, there is no region in the entire world where LGBTQIA+ individuals make up anything more than a small minority. Thus, this minority stress forms a central part of the LGBTQIA+ experience in an extremely universal way. To this day, we have always been a part of the “counterculture”.

Healing and Safe Spaces

When considering the mental health struggles LGBTQIA+ individuals go through, it would be remiss not to cover what factors can alleviate this suffering. A general trend that emerges is that LGBTQIA+ individuals experience better mental health outcomes when exposed to an accepting and affirming environment that does not try to “correct” their identities. For example, a study in California found that family acceptance of LGBT youth predicted greater self-esteem, social support, and general health status, and protected against depression, substance abuse, and suicidal behaviors [14]. Later research in Brazil that focused specifically on transgender and nonbinary individuals replicated these findings — people who received affirmation of their gender had higher self-esteem, and this translated into lower rates of home abandonment among youth [15]. As many members of the community can tell you, the acceptance of those closest to us can help lessen minority stress.

However, given that LGBTQIA+ people often do not receive the social acceptance and belonging we deserve from those around us, we must seek other environments to achieve a sense of belonging. Once we realize our identities, it is incumbent on us to reach out, to find and discover our communities. LGBTQIA+ majority geographical areas are almost nonexistent, so the spaces where we come together are often virtual, and results in much greater accessibility to people who are not in accepting environments. In keeping with this, research suggests that LGBTQIA+ people use social networking sites differently than their heterosexual counterparts, using such platforms primarily for community finding as compared to the general networking and expression that heterosexual people use social media for [16]. While general networking on social media is associated with negative effects on mental health, the community networking LGBTQIA+ people do is associated with positive effects on their well-being. This trend is particularly prominent in younger people, to the extent that they are able to explore their identities flexibly even as they reach out to online communities.


In sum, current research shows that the LGBTQIA+ experience is natural, and influenced by a variety of biological neurological factors. While research on human sexuality and gender is critical to our current understanding of it, that understanding remains vastly incomplete. It’s important to note that the lack of research on LGBTQIA+ identities means that the most current hypotheses behind the development of sex, gender, and sexual orientation are often many years old. Even now, scientists formulating them, including Dr. Ray Blanchard, often harbor bias against the very individuals they studied, and because social progress for the LGBTQIA+ community has been so recent, even more recent hypotheses are not always humanistic. As science and society progress alike, researchers must question earlier findings, think more critically about their own biases, and move toward a worldview that is inclusive of all identities and does not “other” them.

In addition, the experiences of mental illness among the LGBTQIA+ community also remain understudied due to the hidden nature of these identities and mental illness. The internet will be a major help in reaching out to the community while allowing for anonymity. In addition, studies targeted toward homosexual males have historically been greatly overrepresented in the field. More research is desperately needed to study these complex topics, and far more effort to include less visible identities. For the well-being and safety of the LGBTQIA+ community, we must strive to make this a priority.

As a marginalized group of people today, LGBTQIA+ individuals face barriers throughout society. Humanity is responsible for understanding these experiences, amplifying LGBTQIA+ voices, unlearning biases, calling out discrimination when seen, and making material contributions to achieve equity. Here, we have explored the LGBTQIA+ experience from evolutionary, neurological, and psychological perspectives, thus beginning a small portion of understanding the LGBTQIA+ experience.


  1. Monk, J. D., Giglio, E., Kamath, A., Lambert, M. R., & McDonough, C. E. (2019). An alternative hypothesis for the evolution of same-sex sexual behaviour in animals. Nature Ecology & Evolution, 3(12), 1622-1631. doi:10.1038/s41559-019-1019-7
  2. McCarthy, D. A., & Young, C. M. (2002). Gametogenesis and reproductive behavior in the echinoid Lytechinus variegatus. Marine Ecology Progress Series, 233, 157-168. doi:10.3354/meps233157
  3. Young, C. M., Tyler, P. A., Cameron, J. L., & Rumrill, S. G. (1992). Seasonal breeding aggregations in low-density populations of the bathyal echinoid Stylocidaris lineata. Marine Biology, 113(4), 603-612. doi:10.1007/bf00349704
  4. Han, C. S., & Brooks, R. C. (2015). Same-sex sexual behaviour as a by-product of reproductive strategy under male–male scramble competition. Animal Behaviour, 108, 193-197. doi:10.1016/j.anbehav.2015.07.035
  5. Votinov, M., Goerlich, K. S., Puiu, A. A., Smith, E., Nickl-Jockschat, T., Derntl, B., & Habel, U. (2021). Brain structure changes associated with sexual orientation. Scientific Reports, 11(1). doi:10.1038/s41598-021-84496-z
  6. Meyer-Bahlburg, H. F., Dolezal, C., Baker, S. W., & New, M. I. (2007). Sexual orientation in women with classical or non-classical congenital adrenal hyperplasia as a function of degree of prenatal androgen excess. Archives of Sexual Behavior, 37(1), 85-99. doi:10.1007/s10508-007-9265-1
  7. Blanchard, R. (2001). Fraternal birth order and the maternal Immune hypothesis of male homosexuality. Hormones and Behavior, 40(2), 105-114. doi:10.1006/hbeh.2001.1681
  8. Bogaert, A. F., Skorska, M. N., Wang, C., Gabrie, J., MacNeil, A. J., Hoffarth, M. R., . . . Blanchard, R. (2017). Male homosexuality and maternal immune responsivity to the Y-linked protein NLGN4Y. Proceedings of the National Academy of Sciences, 115(2), 302-306. doi:10.1073/pnas.1705895114
  9. Baams, L., Grossman, A. H., & Russell, S. T. (2015). Minority stress and mechanisms of risk for depression and suicidal ideation among lesbian, gay, and bisexual youth. Developmental Psychology, 51(5), 688-696. doi:10.1037/a0038994
  10. Kittiteerasack, P., Steffen, A., & Matthews, A. (2020). The influence of minority stress on level of depression among Thai LGBT adults. Jurnal Keperawatan Indonesia, 23(1), 74-84. doi:10.7454/jki.v23i1.1073
  11. Budge, S. L., Adelson, J. L., & Howard, K. A. (2013). Anxiety and depression in transgender individuals: The roles of transition status, loss, social support, and coping. Journal of Consulting and Clinical Psychology, 81(3), 545-557. doi:10.1037/a0031774
  12. Bryan, A., & Mayock, P. (2016). Supporting LGBT lives? Complicating the Suicide consensus in LGBT mental health research. Sexualities, 20(1-2), 65-85. doi:10.1177/1363460716648099
  13. Toomey, R. B., Syvertsen, A. K., & Shramko, M. (2018). Transgender adolescent suicide behavior. Pediatrics, 142(4), e20174218. doi:10.1542/peds.2017-4218
  14. Ryan, C., Russell, S. T., Huebner, D., Diaz, R., & Sanchez, J. (2010). Family acceptance in adolescence and the health of LGBT young adults. Journal of Child and Adolescent Psychiatric Nursing, 23(4), 205-213. doi:10.1111/j.1744-6171.2010.00246.x
  15. Seibel, B. L., De Brito Silva, B., Fontanari, A. M., Catelan, R. F., Bercht, A. M., Stucky, J. L., . . . Costa, A. B. (2018). The impact of the parental support on risk factors in the process of gender affirmation of transgender and gender diverse people. Frontiers in Psychology, 9(399). doi:10.3389/fpsyg.2018.00399
  16. Ceglarek, P. J., & Ward, L. M. (2016). A tool for help or harm? How associations between social networking use, social support, and mental health differ for sexual minority and heterosexual youth. Computers in Human Behavior, 65, 201-209. doi:10.1016/j.chb.2016.07.051