Gender vs. Sex and Beyond the Binary

The argument and/or question

Anti-trans activists and TERFs often make the following claims about gender and sex:

• “Gender and sex are the same thing.”

• “Gender is just a politically correct term for biological sex.”

• “Sex is binary, immutable, and determines gender.”

• “If gender and sex are different, why do trans people modify their bodies to align with their gender?”

• “Gender identity is made-up nonsense invented by John Money.”

These arguments typically rest on an oversimplified understanding of both biology and gender. They present sex as a simple, binary, unchangeable characteristic determined at birth, while dismissing gender as either identical to sex or a meaningless “feeling” with no basis in reality.

The underlying goal is to delegitimize trans identities by creating a false dichotomy: either gender equals sex (making trans identities impossible), or gender is completely separate from sex (making it seem like a trivial preference disconnected from any material reality).

The Answer and/or Response

Gender and sex are related but distinct concepts with multiple facets. Research reveals that gender encompasses physiological/bodily aspects (sex), gender identity (self-defined gender), legal gender, and social gender (norm-related behaviors and expressions).¹

Neither sex nor gender is a simple binary. Biological sex exists on a spectrum with multiple variables including chromosomes, hormones, gonads, and genitalia that don't always align in the expected patterns. Research has shown that approximately 1.7% of people have intersex traits, roughly the same percentage as people born with red hair.²

The relationship between gender and sex is complex and bidirectional. While they're distinct, they're not completely separate domains. Evidence suggests that gender identity has biological components influenced by prenatal hormone exposure and brain development.³ At the same time, our understanding and experience of our own bodies (including sex characteristics) is mediated through gendered concepts and language.⁴

Some people have a gender that is neither male nor female and may identify as both genders simultaneously, as different genders at different times, as no gender at all, or dispute the very idea of only two genders. The umbrella terms for such genders are “genderqueer” or “non-binary.”⁵

Discussion

Let's dive deeper into this relationship between gender and sex, because honestly, it's a lot more interesting and complex than the “boys have penises, girls have vaginas” lesson from kindergarten.

The gender binary framework—the view that humans comprise only two types of beings, women and men—has profoundly shaped psychological science, but is now facing serious challenges from both academic research and social activism.⁶

According to Hyde and colleagues, five major scientific areas fundamentally undermine the gender binary:

1. Neuroscience findings refute sexual dimorphism of the human brain

2. Behavioral neuroendocrinology challenges the notion of genetically fixed, non-overlapping hormonal systems

3. Psychological research highlights the similarities between men and women

4. Studies on transgender and nonbinary individuals' identities and experiences

5. Developmental research showing that viewing gender/sex as a binary category is culturally determined and malleable⁷

First, biological sex itself is more complicated than most people realize. Sex determination and differentiation involves multiple biological systems:

• Genetic sex (typically XX or XY, but variations exist)

• Gonadal sex (testes or ovaries)

• Hormonal sex (predominance of testosterone or estrogen)

• Morphological sex (external and internal reproductive structures)

• Neurological sex (brain structures and patterns)

These don't always align in the expected ways. People can have XY chromosomes but develop female external genitalia due to androgen insensitivity syndrome. Others may have XX chromosomes but develop primarily male-typical anatomy due to congenital adrenal hyperplasia. Some people have XXY, XYY, or other chromosomal variations.⁸

As Anne Fausto-Sterling notes, “There is no either/or. Rather, there are shades of difference.”⁹ Nature's extensive article “Sex Redefined” similarly concludes that “biologists now think there is a wider spectrum than that.”¹⁰

The existence of intersex people isn't just a rare exception—it fundamentally challenges the idea that sex is a simple binary rather than a bimodal distribution with significant overlap and variation.¹¹

Similarly, gender isn't just about social roles or stereotypes. It has biological components as well. Studies of transgender individuals consistently show differences in brain structure and function that align more closely with their gender identity than their assigned sex at birth.¹² Some research has identified genetic polymorphisms associated with gender identity, suggesting a heritable component.¹³ Research with intersex individuals who were assigned a gender at birth that didn't match their gender identity shows that gender identity persists despite socialization efforts, suggesting an innate component to gender.¹⁴

What's particularly fascinating is how the relationship between gender and sex works in both directions. Our biology influences our gender identity, but our gender identity also influences how we perceive, experience, and modify our bodies.

Consider hormone replacement therapy (HRT) for transgender people. Taking estrogen or testosterone doesn't just change secondary sex characteristics—it changes how one feels in their body, how one experiences emotions, sexual desire, and even cognitive patterns.¹⁵ In other words, hormonal sex influences psychological aspects of gender, and changing hormonal sex changes the lived experience of gender.

As psychologist Meg-John Barker puts it: “Our bodies and our sense of who we are are not separate things.”¹⁶

This also explains why the “gender is just stereotypes” argument falls flat. Trans people don't transition because they like pink or blue, or because they prefer dresses to pants. They transition because of a profound incongruence between their internal sense of self and their physical characteristics. Research with transgender children who are supported in their identities shows mental health outcomes comparable to their cisgender peers, demonstrating that affirming gender identity is associated with well-being.¹⁷

For non-binary individuals, these identities are not disorders or pathological conditions, but legitimate expressions of gender that are increasingly recognized in legal, medical, and psychological systems.¹⁸ Population-based studies show that while non-binary individuals represent a small percentage of the population, they constitute a sizable number of people in raw terms. While such gender expressions have existed historically and globally, they remain marginalized, putting these individuals at risk of victimization and minority stress due to discrimination.¹⁹

The practice of measuring gender as a dichotomous variable (woman/man or female/male) in research is increasingly recognized as problematic because it leads to measurement errors, discriminates against non-binary individuals, and reinforces binary notions of gender.²⁰

Logical Fallacies

Now let's address some of the logical fallacies that TERFs employ when discussing gender and sex:

False Dichotomy: TERFs present only two options—either gender equals sex, or gender is completely separate from sex. This ignores the complex, bidirectional relationship between the two concepts.

Appeal to Nature: The argument that sex is “natural” while gender is “artificial” ignores that all human categories, including biological ones, are interpreted through social and cultural lenses. We don't directly perceive chromosomes; we create frameworks to understand biological reality.²¹

Fallacy of Division: Assuming that because “biological sex” has certain properties as a collective concept, each individual aspect of sex must have those same properties. For instance, because “biological sex” is seen as binary, they assume every aspect of sex (chromosomes, hormones, etc.) must also be binary.

Category Error: Treating sex and gender as comparable types of things. Sex refers to biological characteristics, while gender refers to psychological and social phenomena. They're related but different domains, like comparing the physical structure of the brain to consciousness.

Etymological Fallacy: Assuming that because “gender” originally referred to grammatical categories, it can't validly refer to psychological identity. This ignores how language evolves.

The Science vs. The Politics

Here's what's truly baffling about this whole debate. The actual science is pretty clear, and has been for decades. Medical associations worldwide recognize the validity of transgender identities and the effectiveness of gender-affirming care.²²

The American Psychological Association, American Medical Association, American Academy of Pediatrics, and countless other scientific and medical organizations have position statements affirming that:

1. Being transgender is not a mental illness

2. Gender identity has biological components

3. Gender-affirming care is effective and life-saving

4. Conversion therapy attempting to change gender identity is harmful²³

So why are we still arguing about this?

Well, it's almost as if this isn't actually about scientific truth but about maintaining a comfortable worldview where gender and sex always align neatly, and anyone who falls outside that pattern can be dismissed as confused, mentally ill, or following a 'trend.'

It's a lot like climate change denial. When the science becomes inconvenient for your political position, you don't change your position—you try to discredit the science.

And just like climate denial, the anti-trans position requires ignoring mountains of evidence and the consensus of experts in the relevant fields. It requires cherry-picking studies, misrepresenting research, and creating a parallel universe of “alternative facts.”

As Julia Serano notes, transmisic (anti-trans) rhetoric often functions as a distraction tactic, using “gotcha” questions and semantic games to draw attention away from the lived experiences of trans people.²⁴

Moving Toward Better Understanding

The choice of how to operationalize gender in research and society should be driven by specific context and needs rather than rigid dogma. Researchers are increasingly encouraged to reflect on why they include gender as a variable and which aspects of gender are most relevant to their study.²⁵

For health professionals, understanding these complexities is crucial. Treatment options for individuals with non-binary genders must acknowledge both the legitimacy of these identities and the potential risks associated with various interventions.²⁶

Instead of forcing everyone into binary categories, we should consider alternatives such as:

• Adding third or multiple categories for gender identity

• Using free-text responses that allow individuals to self-define their gender

• Employing measures that assess femininity and masculinity as independent dimensions

• Measuring the importance of identification with one's gender²⁷

Conclusion

The relationship between gender and sex is complex, multifaceted, and exists beyond simple binaries. Scientific evidence from neuroscience, psychology, endocrinology, and developmental studies all support this more nuanced understanding.

Non-binary and transgender identities are not new phenomena—they have existed throughout history and across cultures. What's new is our growing scientific understanding of the biological and psychological underpinnings of gender diversity.

The costs of relying on the gender binary are substantial: it harms those who don't fit neatly into categorical boxes, it impedes scientific progress by imposing artificial dichotomies on complex phenomena, and it limits our collective understanding of human diversity.²⁸

By embracing a more nuanced view of gender and sex—one supported by current scientific evidence—we can create a more accurate, inclusive, and compassionate framework for understanding the full spectrum of human gender experiences.

Trans people's experiences offer particularly valuable insights into this relationship, demonstrating how deeply interconnected these aspects of human identity really are. Far from contradicting biology, transgender identities help us develop a more accurate and nuanced understanding of the relationship between gender and sex.

The next time someone tries to shut down a conversation about transgender rights by shouting “basic biology!” remember that actual biology—the complex, messy, fascinating science studied by real biologists—supports transgender experiences. What doesn't support them is the oversimplified “boys have penises, girls have vaginas” version of biology that we teach to five-year-olds because they're not ready for the complicated truth.

Real science embraces complexity. And in that complexity, trans people's experiences make perfect sense.

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References

1. Hyde, J. S., Bigler, R. S., Joel, D., Tate, C. C., & van Anders, S. M. (2019). The future of sex and gender in psychology: Five challenges to the gender binary. American Psychologist, 74(2), 171–193. https://doi.org/10.1037/amp0000307

2. Blackless, M., Charuvastra, A., Derryck, A., Fausto-Sterling, A., Lauzanne, K., & Lee, E. (2000). How sexually dimorphic are we? Review and synthesis. American Journal of Human Biology, 12(2), 151-166. https://doi.org/10.1002/(sici)1520-6300(200003/04)12:2%3C151::aid-ajhb1%3E3.0.co;2-f

3. Hare, L., Bernard, P., Sánchez, F. J., Baird, P. N., Vilain, E., Kennedy, T., & Harley, V. R. (2009). Androgen receptor repeat length polymorphism associated with male-to-female transsexualism. Biological Psychiatry, 65(1), 93-96. https://doi.org/10.1016/j.biopsych.2008.08.033

4. Butler, J. (1990). Gender trouble: Feminism and the subversion of identity. Routledge.

5. Richards, C., Bouman, W. P., Seal, L., Barker, M. J., Nieder, T. O., & T'Sjoen, G. (2016). Non-binary or genderqueer genders. International Review of Psychiatry, 28(1), 95-102. https://doi.org/10.3109/09540261.2015.1106446

6. See 1 above.

7. Ibid.

8. Fausto-Sterling, A. (2012). Sex/gender: Biology in a social world. Routledge.

9. See 2 above.

10. Ainsworth, C. (2015). Sex redefined. Nature, 518(7539), 288-291. https://doi.org/10.1038/518288a

11. See 2 above.

12. Guillamon, A., Junque, C., & Gómez-Gil, E. (2016). A review of the status of brain structure research in transsexualism. Archives of Sexual Behavior, 45(7), 1615-1648. https://doi.org/10.1007/s10508-016-0768-5

13. See 3 above.

14. Reiner, W. G., & Gearhart, J. P. (2004). Discordant sexual identity in some genetic males with cloacal exstrophy assigned to female sex at birth. New England Journal of Medicine, 350(4), 333-341. DOI: 10.1056/NEJMoa022236

15. Nguyen, H. B., Loughead, J., Lipner, E., Hantsoo, L., Kornfield, S. L., & Epperson, C. N. (2019). What has sex got to do with it? The role of hormones in the transgender brain. Neuropsychopharmacology, 44(1), 22-37. https://doi.org/10.1038/s41386-018-0140-7

16. Barker, M. J. (2017). Gender, sexual, and relationship diversity (GSRD). British Association for Counselling and Psychotherapy. https://www.bacp.co.uk/media/5877/bacp-gender-sexual-relationship-diversity-gpacp001-april19.pdf

17. Olson, K. R., Durwood, L., DeMeules, M., & McLaughlin, K. A. (2016). Mental Health of Transgender Children Who Are Supported in Their Identities. Pediatrics, 137(3), e20153223. https://doi.org/10.1542/peds.2015-3223.

18. See 5 above.

19. Ibid.

20. See 1 above.

21. See 8 above.

22. Coleman, E., Bockting, W., Botzer, M., Cohen-Kettenis, P., DeCuypere, G., Feldman, J., Fraser, L., Green, J., Knudson, G., Meyer, W. J., Monstrey, S., Adler, R. K., Brown, G. R., Devor, A. H., Ehrbar, R., Ettner, R., Eyler, E., Garofalo, R., Karasic, D. H., … Zucker, K. (2012). Standards of Care for the Health of Transsexual, Transgender, and Gender-Nonconforming People, Version 7. International Journal of Transgenderism, 13(4), 165–232.

23. Rafferty, J., Committee on Psychosocial Aspects of Child and Family Health, Committee on Adolescence, & Section on Lesbian, Gay, Bisexual, and Transgender Health and Wellness. (2018). Ensuring comprehensive care and support for transgender and gender-diverse children and adolescents. Pediatrics, 142(4), e20182162. https://doi.org/10.1542/peds.2023-063756

24. Serano, J. (2016). Whipping girl: A transsexual woman on sexism and the scapegoating of femininity. Seal Press.

25. See 1 above.

26. See 5 above.

27. See 1 above.

28. Ibid.