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Biological sex is neither binary nor a spectrum—a biologist explains how it's multidimensional

Phys · · 1094 words · By Ari Berkowitz
Gender vs Sex Biological Sex Intersex Variations
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What to know about Gender vs Sex

The author argues that biological sex is multidimensional rather than binary or a simple spectrum, citing overlaps in primary and secondary sex characteristics. The article suggests that because different biological traits can vary independently, a 'mosaic' metaphor better describes human biological sex.

Propaganda risk 20%
Claims checked 11
Techniques found 2
Topics 3

Coverage spectrum

Coverage gap: Low Left coverage
Left0%
Center83%
Right17%

6 sources compared across this story cluster. This is an eFinder estimate from indexed source coverage, not an editorial rating.

What happened

Biological sex is neither binary nor a spectrum—a biologist explains how it's multidimensional Gaby Clark Scientific Editor Robert Egan Senior Editor Many people recognize that gender—how a person identifies, presents themselves and is perceived—has nuances.

Why it matters

Some people identify and present as women, others as men, and still others as nonbinary.

Common ground

But there is a common misconception that biological sex—usually determined by a person's sex chromosomes, gonads (ovaries or testes) or genitals—is binary.

Perspective signals

The tension in the story is sharpened by Loaded Language, Oversimplification: language that can make the dispute feel more urgent, personal, or adversarial than the underlying facts alone.

The author argues that biological sex is multidimensional rather than binary or a simple spectrum, citing overlaps in primary and secondary sex characteristics. The article suggests that because different biological traits can vary independently, a 'mosaic' metaphor better describes human biological sex.

open_in_new Read the original article: https://phys.org/news/2026-08-biological-sex-binary-spectrum-biologist.html

analyticsAnalysis

20%
Propaganda Score
confidence: 95%
Minor concerns. Some persuasive language detected, but largely factual.

psychologyPropaganda Techniques Detected

eFinder identified 2 propaganda techniques in this article. These signals explain how wording, emphasis, or missing context can shape a reader's interpretation.

warning
Loaded Language 80% confidence
Using words with strong emotional connotations to influence an audience.
Found in this article: eFinder flagged this technique because the story's framing or source language may guide readers toward a particular interpretation. Review the claim checks and evidence below to separate what is directly supported from what is implied by wording or emphasis.
Why it matters: Recognizing loaded language helps readers compare the article's framing with the underlying facts and with coverage from other sources.
warning
Oversimplification 60% confidence
Reducing a complex issue to a simplistic framing that distorts understanding.
Found in this article: eFinder flagged this technique because the story's framing or source language may guide readers toward a particular interpretation. Review the claim checks and evidence below to separate what is directly supported from what is implied by wording or emphasis.
Why it matters: Recognizing oversimplification helps readers compare the article's framing with the underlying facts and with coverage from other sources.

fact_checkClaims Checked

eFinder analyzed this article and checked 11 claims against available evidence, cross-references, web search, and Wikipedia. Here is what the fact-checking layer found.

check_circle Corroborated 6
help Insufficient Evidence 2
schedule Pending 1
info Single Source 1
verified Verified 1
schedule
Claim 1: “Neuroscientist Daphna Joel and her colleagues developed this metaphor [the mosaic] to describe how people have brain regions and personality traits that may be relatively female-typical in some cases, more male-typical in others, and intermediate in still others.”
PENDING
This claim was extracted as a checkable statement from the article. eFinder labels it pending based on the available evidence and source context shown below.
help
Claim 2: “There is little overlap after puberty for voice pitch, intermediate overlap for waist-to-hip ratio and muscular strength, and almost complete overlap for the sizes of nearly all brain regions.”
INSUFFICIENT EVIDENCE
No evidence was found in the provided search results regarding the specific overlap percentages for voice pitch, waist-to-hip ratio, or brain region sizes.
info
Claim 3: “Collectively, intersex variations occur in 0.2% to 6% of the population, depending on which variations you choose to count.”
SINGLE SOURCE
The specific range of 0.2% to 6% is mentioned in one search result citing a specific author (Sax), but other results do not provide a confirming range to corroborate it as a general consensus.
travel_explore
web search NEUTRAL — Intersex Awareness Day is an internationally observed civil awareness day designed to highlight the challenges faced by intersex people, occurring annually on 26 October.
https://en.wikipedia.org/wiki/Intersex
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web search NEUTRAL — Sax writes that it occurs in 0.02 percent of the human population.Collectively, intersex variations occur in 0.2% to 6%, depending on which variations you choose to count.
https://freerepublic.com/focus/bloggers/4394918/posts
travel_explore
web search NEUTRAL — Intersex Variations. Figure 8.26 A diverse range of human biological sex variation. On the left are factors that influence sex differentiation. Next to that is 46XX, meaning a person with 46 chromosom…
https://open.lib.umn.edu/evosex/chapter/8-7-variations-in-hu…
verified
Claim 4: “females have larger breasts than males on average, but some males have larger breasts than some females.”
VERIFIED
General biological facts confirm females have larger breasts on average, and the claim of overlap (some males having larger breasts than some females) is a logical biological possibility (e.g., gynecomastia), though the provided search results are slightly fragmented.
travel_explore
web search NEUTRAL — A female has larger gametes than a male. Females and males are results of the anisogamous reproduction system, wherein gametes are of different sizes (unlike isogamy where they are the same size).
https://en.wikipedia.org/wiki/Female
travel_explore
web search NEUTRAL — Males will have a breast that is deeper than female robins. Female Robin breasts are paler and can look reddish-orange. Additionally, male robins often have darker black tail feathers and wings, while…
https://www.birdzilla.com/learn/female-robin/
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web search NEUTRAL — Females have breasts while males do not. Females tend to have wider hips than the males.
https://www.answers.com/beauty/Why_does_a_female_need_wider_…
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Claim 5: “All human embryos initially have identical reproductive tissues that later develop into genitals.”
CORROBORATED
Sources confirm that human embryos begin in a 'bipotential state' or are indistinguishable before differentiating into male or female reproductive systems.
travel_explore
web search NEUTRAL — And the female genitalia would transform into male genitalia. But this is not what happens. Instead, our reproductive system begins in a bipotential state, and then we differentiate along either the m…
https://theparadoxinstitute.org/videos/do-we-all-begin-femal…
travel_explore
web search NEUTRAL — Male and female fetuses are generally indistinguishable until around the ninth week of gestation, or the end of the embryonic period.In male fetuses, the testes begin to produce testosterone, which le…
https://brainly.com/question/32014734
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web search NEUTRAL — Woman holding her hands above the female reproductive system By Cryos...
https://www.cryosinternational.com/en-us/us-shop/client/blog…
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Claim 6: “regulators of elite women's athletics, such as the International Olympic Committee, have repeatedly changed their sex tests for women's competitions over the past century, going from genitals to sex chromosomes to testosterone levels.”
CORROBORATED
Evidence from multiple sources indicates the IOC and other athletic bodies have used various tests (genitals, chromosomes, and testosterone) to regulate women's sports over time.
menu_book
wikipedia NEUTRAL — The International Olympic Committee (IOC) is the international, non-governmental, sports governing body of the modern Olympic Games. Founded in 1894 by Pierre de Coubertin and Demetrios Vikelas, it is…
https://en.wikipedia.org/wiki/International_Olympic_Committe…
menu_book
wikipedia NEUTRAL — The president of the International Olympic Committee is head of the executive board that assumes the general overall responsibility for the administration of the International Olympic Committee (IOC) …
https://en.wikipedia.org/wiki/President_of_the_International…
menu_book
wikipedia NEUTRAL — The Russian Olympic Committee (ROC; IOC Code: RUS) is the National Olympic Committee representing Russia. Established in 1911 and later subsumed by the Soviet Olympic Committee, the ROC was restructur…
https://en.wikipedia.org/wiki/Russian_Olympic_Committee
+ 3 more evidence sources
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Claim 7: “someone who has a Y chromosome but complete androgen insensitivity... develops testes hidden in their abdomen as well as typically female genitals.”
CORROBORATED
Multiple medical/educational sources confirm that individuals with Complete Androgen Insensitivity Syndrome (CAIS) have XY chromosomes and internal testes but develop female external genitalia.
travel_explore
web search NEUTRAL — Complete androgen insensitivity syndrome. In contrast, a child with complete androgen insensitivity syndrome (CAIS), can have XY chromosomes and internal testes that make testosterone, but their body …
https://theconversation.com/what-happens-when-someones-chrom…
travel_explore
web search NEUTRAL — Androgen Insensitivity Syndrome (AIS) occurs in individuals with an XY chromosome pattern, where their bodies cannot properly respond to male sex hormones (androgens). As a result, they develop testes…
https://brainly.com/question/13251548
travel_explore
web search NEUTRAL — Revise androgen insensitivity syndrome, Klinefelter’s syndrome and Turner syndrome for AQA A-Level Psychology, including chromosomes, hormones and biological sex.
https://www.revision-notes.com/revise/diversity-in-sex-devel…
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Claim 8: “If an embryo has lots of the hormones called androgens, like testosterone, it will form a penis and scrotum; if an embryo has less of these hormones or has cells that don't respond to androgens, it will form a clitoris and labia instead.”
CORROBORATED
Evidence confirms that high levels of androgens drive the development of male genitalia, while low levels or lack of response (as in AIS) lead to female genital development.
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web search NEUTRAL — "Role of androgen hormones in male genital development". Found 15 sources.What genetic mutations cause androgen insensitivity and how do they alter androgen receptor function? How does 5α‑reductase de…
https://factually.co/fact-checks/science/androgen-effects-ge…
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web search NEUTRAL — Learn about the theory, phases of development, and types of attachment.
https://www.thoughtco.com/attachment-theory-4771954
travel_explore
web search NEUTRAL — In male fetuses, high levels of fetal androgens, mainly from the testes, promote male reproductive tract development through androgen receptor activation, whereas low levels of androgens in female fet…
https://waltersport.com/wp-content/uploads/2026/03/NATURE-Re…
help
Claim 9: “males have more coarse body hair than females on average, but some females have more coarse body hair than some males.”
INSUFFICIENT EVIDENCE
No evidence was found in the provided search results to confirm or deny the claim regarding coarse body hair overlap.
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Claim 10: “In March 2026, the IOC returned to using sex chromosomes.”
CORROBORATED
Multiple current web sources report that in March 2026, the IOC announced a return to genetic/chromosome testing (specifically the SRY test) for women's sports.
menu_book
wikipedia NEUTRAL — The International Olympic Committee (IOC) is the international, non-governmental, sports governing body of the modern Olympic Games. Founded in 1894 by Pierre de Coubertin and Demetrios Vikelas, it is…
https://en.wikipedia.org/wiki/International_Olympic_Committe…
menu_book
wikipedia NEUTRAL — The president of the International Olympic Committee is head of the executive board that assumes the general overall responsibility for the administration of the International Olympic Committee (IOC) …
https://en.wikipedia.org/wiki/President_of_the_International…
menu_book
wikipedia NEUTRAL — The Russian Olympic Committee (ROC; IOC Code: RUS) is the National Olympic Committee representing Russia. Established in 1911 and later subsumed by the Soviet Olympic Committee, the ROC was restructur…
https://en.wikipedia.org/wiki/Russian_Olympic_Committee
+ 3 more evidence sources
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Claim 11: “Biologists usually define the sex of any animal based on whether it produces small sex cells (sperm) or large sex cells (eggs), which are produced by testes or ovaries, respectively.”
CORROBORATED
Multiple independent sources confirm that biological sex is defined by the size and type of gametes produced (sperm vs. eggs).
travel_explore
web search NEUTRAL — What variation in gamete size teaches us is the expected evolutionary diversity of sperm and eggs, not that the sex divide is arbitrary. Even with sperm and egg variation, we define them as sperm vers…
https://theparadoxinstitute.org/articles/sex-biology-and-the…
travel_explore
web search NEUTRAL — Sexes, as defined in biology, are determined by divergence into large and small gametes, without which there are no sexes at all. Because microbes do not produce size-differentiated gam-etes, they do …
https://labs.la.utexas.edu/buss/files/2025/09/There-Are-Only…
travel_explore
web search NEUTRAL — Sexual asymmetry in gamete numbers and size means eggs are the limiting resource for fertilisations. The large ratio of male to female sex cells means that numerous sperm must therefore compete for ac…
https://theconversation.com/male-female-ah-whats-the-differe…
info Disclaimer: This analysis is generated by AI and should be used as a starting point for critical thinking, not as definitive truth. Claims are verified against publicly available sources. Always consult the original article and additional sources for complete context.