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Biological sex

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Biological sex is a term that refers to, and is defined by, numerous biological markers in humans and other organisms: sex chromosomes, genitals, gonads, gametes, hormones and secondary sex characteristics. The two main categories of biological sex are "female" and "male", each referring to a specific combination of markers (XX chromosomes, vagina, ovaries, ova, estrogen, breasts etc. for female, and XY chromosomes, penis, testes, sperm, androgens etc. for male.)

Sex as a spectrum[edit]

Scientific research on biological sex has dismantled the traditional idea that "male" and "female" form a collectively exhaustive binary, with articles and papers in the Scientific American, Nature etc. indicating that these categories represent two ends of a spectrum.[1][2]

While the vast majority of human beings fall neatly at one end or the other, there are also many people in whom some of the markers of biological sex point to "male" and others to "female" (and others to neither). These include people born with intersex variations, XY women with androgen insensitivity syndrome, people with chromosome configurations other than XX and XY, etc. The frequency of live births that deviate from the two binary categories may be as high as 1.7%[3] or even 2%.[4]

Transgender people[edit]

In addition to those described above, transgender people who are medically transitioning also defy the binary categories, because the medical procedures involved (hormone therapy, surgery etc.) will alter some of the biological markers that dictate the person's biological sex, so that they no longer all line up as "male" or "female".[note 1] Therefore, for all intents and purposes, a transgender person's "biological sex" may well have shifted along the spectrum away from their sex assigned at birth.

The practice of referring to transgender people as their birth sex is not simply politically incorrect; it is factually incorrect, and this terminology is increasingly being rejected by medical professionals.[5] In any case, a doctor who wants to know the biological sex of a transgender patient will most likely want all the relevant information, not just a traditional binary sex label, the same as would be the case with a patient who is intersex.

Sex binarism and bigotry[edit]

Sex binarism refers to the belief in, and attempts to re-enforce, a mutually exclusive and collectively exhaustive dichotomy of "male" and "female" for everyone. This attitude is at the root of a large amount of real-world harm. One example is the fact that medical operations are commonly performed on intersex individuals, including children who cannot consent, for cosmetic purposes;[6] peak bodies such as the United Nations and the Council of Europe are calling for this practice to be abolished.[7][8][9]

Sex binarism also forms the bedrock of anti-trans bigotry, with TERFs and other transphobes often attempting to reify the notion of sex assigned at birth as a person's "true" sex. This idea has no basis and flies in the face of the above information regarding the scientific research, as well as the many people who do not fit into the binary.

See also[edit]

External links[edit]



  1. Amanda Montañez. Visualizing Sex as a Spectrum. Scientific American, August 29, 2017.
  2. Claire Ainsworth. Sex redefined. Nature, February 18, 2015.
  3. Anne Fausto-Sterling. Sexing the Body: Gender Politics and the Construction of Sexuality. Hachette UK, 2008.
  4. Melanie Blackless, Anthony Charuvastra, Amanda Derryck, Anne Fausto-Sterling, Karl Lauzanne, Ellen Lee. How sexually dimorphic are we? Review and synthesis. American Journal of Human Biology 12(2), March 2000, pp. 151-166.
  5. Zinnia Jones. Medical professionals increasingly agree: Trans women are female, trans men are male. GenderAnalysis.net, October 1, 2017.
  6. Eliminating forced, coercive and otherwise involuntary sterilization, An interagency statement, World Health Organization, May 2014.
  7. Intersex Awareness Day – Wednesday 26 October. United Nations Human Rights: Office of the High Commissioner.
  8. Report of the Special Rapporteur on torture and other cruel, inhuman or degrading treatment or punishment, Juan E. Méndez. United Nations General Assembly, February 1, 2013.
  9. Human rights and intersex people. Council of Europe Commissioner for Human Rights.