The Two Gender Argument is Ignorant

When we’re young and studying human biology we’re introduced to a simplified gender concept to help us understand why genders exist. We’re told that XX chromosomes make you female, and XY chromosomes make you male. And for the most part, this is true. These chromosomes, found in nearly every cell, are like tightly packed instruction manuals made of DNA, guiding our development.

As a brief aside, this article is going to talk a lot about specific types of biological differentiation, but here’s a brief section of a lecture from a professor at Stanford that sheds related light before we get into the meat of this topic.

And here another scientific discussion to warm things up before we really get into it.

Let’s Begin…

The XX/XY system determines sex for the vast majority of people. And while this system is true for about 98% of the human population, biological reality is more diverse. Natural variations in chromosomes, hormones, and physical anatomy mean some individuals don’t fit neatly into typical male or female boxes. These variations are often grouped under terms like Differences of Sex Development (DSDs) or Intersex traits. The variations aren’t abnormalities in a negative sense; they’re documented examples of natural human biological diversity.

How common is this? As I said, well over 98% of people have the typical XX or XY chromosomal patterns, but up to 1.7%, or nearly 1 in 50 people, are born with characteristics that vary from standard male or female norms! That’s roughly as common as people born with red hair – or roughly 140 MILLION people on the planet!

Even if you take the most conservative estimates and pretend intersex traits only occur in one person in fifty thousand, the popular claim that “every human fits cleanly into male or female with no exceptions” is still false. Science only needs one real counterexample to kill an absolute statement. We do not have one, we have an entire catalog of them. Furthermore, human evolution relies on mutation, and there is no telling how significant of a role these intersex traits have had in the development of the species – because intersex humans DO still procreate.

So you might not be aware of people’s abnormalities because it’s deeply personal and they are used to being attacked for being different, but think about how often you see redheads, and know that’s also how often you see people whose gender don’t align with what’s considered normal. Here’s the story of a person who has spoken publicly about what it’s like to be born different.

Common Variations in Sex Chromosomes

Beyond the typical XX and XY, individuals can have different numbers of sex chromosomes. This fact alone means we’re not dealing with a binary choice. There are several well know variants. By the way I’m skipping the pure variant known now as Intersex or Ovotesticular disorder of sex development (ovotesticular DSD), formerly hermaphroditism, in which a human is born with both a penis and a vagina.

There have been around 500 documented case, so it’s very rare – but it does happen and it completely flies in the face of any argument that there are only 2 sexes, when one person possesses both!

Klinefelter Syndrome (47,XXY)

• Prevalence: Affects about 1 in 500 to 1 in 650 newborn males.
• Technical Explanation: Individuals have an extra X chromosome (47,XXY instead of 46,XY). This typically leads to reduced testosterone production from puberty onwards, affecting physical development and often causing infertility due to impaired sperm production (azoospermia or oligospermia).
• Plain English Summary: Boys and men with Klinefelter Syndrome have an extra X chromosome. They are genetically male but may be taller than average, have less muscle tone, less facial/body hair, and smaller testes. Reduced testosterone can sometimes lead to breast growth (gynecomastia). Many are infertile. Learning differences can sometimes occur.
• Learn More: https://medlineplus.gov/genetics/condition/klinefelter-syndrome/

Turner Syndrome (45,X)

• Prevalence: Affects about 1 in 2,000 to 1 in 2,500 newborn females.
• Technical Explanation: Individuals are missing all or part of one X chromosome (45,X instead of 46,XX). This typically results in gonadal dysgenesis (ovaries don’t develop properly), leading to short stature, infertility, and lack of spontaneous puberty without hormone therapy. Certain physical features like a webbed neck or heart defects can also be present.
• Plain English Summary: Girls and women with Turner Syndrome have one X chromosome instead of two, or part of one X is missing. They are genetically female but are usually shorter than average and don’t develop ovaries properly, meaning they typically don’t go through puberty or menstruate naturally and are infertile. Some may have other physical traits like a wider neck or heart conditions.
• Learn More: https://medlineplus.gov/genetics/condition/turner-syndrome/

Triple X Syndrome (47,XXX)

• Prevalence: Affects about 1 in 1,000 newborn females.
• Technical Explanation: Individuals have an extra X chromosome (47,XXX instead of 46,XX). Many individuals have few or no associated signs or symptoms. Potential characteristics include tall stature, developmental delays (especially in speech and language), learning disabilities, and weaker muscle tone (hypotonia). Fertility is usually normal.
• Plain English Summary: Girls and women with Triple X have an extra X chromosome. Many have no noticeable effects, while some might be taller than average or experience delays in learning, language, or motor skills. Most are fertile and lead typical lives.
• Learn More: https://medlineplus.gov/genetics/condition/triple-x-syndrome/

XYY Syndrome (47,XYY)

• Prevalence: Affects about 1 in 1,000 newborn males.
• Technical Explanation: Individuals have an extra Y chromosome (47,XYY instead of 46,XY). Associated characteristics can include tall stature, severe acne during adolescence, and an increased risk of learning disabilities, speech delays, and behavioral issues like ADHD or autism spectrum disorder. Fertility is usually normal.
• Plain English Summary: Boys and men with XYY syndrome have an extra Y chromosome. They are genetically male and often taller than average. They might face challenges with learning or behavior and may have more acne as teens, but most lead typical lives and are fertile.
• Learn More: https://medlineplus.gov/genetics/condition/47xyy-syndrome/

48,XXXY Syndrome

• Prevalence: Affects approximately 1 in 17,000 to 1 in 50,000 newborn boys.
• Technical Explanation: A chromosomal condition where males have two extra X chromosomes (48,XXXYinstead of 46,XY). It typically leads to testicular dysgenesis and hypergonadotropic hypogonadism, resulting in infertility and low testosterone. Compared to Klinefelter syndrome (47,XXY), individuals with 48,XXXY often present with more pronounced features, including a higher likelihood of intellectual disability (often mild to moderate), significant speech and language delays, developmental delays, hypotonia, distinctive facial features (hypertelorism, epicanthal folds), and skeletal anomalies like radioulnar synostosis and clinodactyly. Behavioral characteristics such as anxiety, short attention span, and impaired social skills are also common.
• Plain English Summary: Boys and men with this rare condition have two extra X chromosomes. They are genetically male but typically experience infertility due to underdeveloped testes and low testosterone. Compared to the more common Klinefelter syndrome (XXY), features are often more significant, including common delays in speech, learning difficulties, and often mild-to-moderate intellectual disability. They may be tall, have low muscle tone, and potentially have specific physical traits like widely spaced eyes or curved pinky fingers. Behavioral challenges like anxiety or attention difficulties can occur more frequently.
• Known Example: Caroline Cossey
• Learn More: https://medlineplus.gov/genetics/condition/48xxxy-syndrome/

Variations Affecting Hormones and Development

Other variations involve typical chromosome pairs (XX or XY) but affect how sex hormones are produced or used, or how anatomy develops.

Androgen Insensitivity Syndrome (AIS)

• Prevalence: Complete AIS (CAIS) affects ~1 in 20,000 to 1 in 50,000 individuals assigned female at birth. Partial AIS (PAIS) is likely similar or slightly more common. Mild AIS (MAIS) is rarer.
• Technical Explanation: Individuals have XY chromosomes and internal testes that produce androgens (like testosterone), but their bodies’ cells cannot fully or partially respond to these hormones due to mutations in the androgen receptor gene (located on the X chromosome). CAIS leads to female external genitalia but no uterus/ovaries. PAIS leads to a range of genital appearances.
• Plain English Summary: People with AIS are genetically male (XY) with internal testes, but their bodies can’t properly use male hormones. In Complete AIS, they develop looking like typical females externally but lack internal female organs and don’t menstruate. In Partial AIS, the body responds somewhat, leading to genitals that might look partly male, partly female, or somewhere in between.
• Learn More: https://medlineplus.gov/genetics/condition/androgen-insensitivity-syndrome/

5-alpha reductase deficiency (5-ARD)

• Prevalence: Rare overall, but more common in certain isolated populations.
• Technical Explanation: Individuals have XY chromosomes and testes. A genetic mutation prevents the body from converting testosterone into the more potent dihydrotestosterone (DHT), which is crucial for masculinizing external genitalia in utero. This results in ambiguous or female-appearing external genitalia at birth. At puberty, the surge in testosterone causes significant virilization.
• Plain English Summary: These individuals are genetically male (XY) with internal testes, but their bodies can’t make a specific strong male hormone (DHT) needed to form male external genitals before birth. They might be born looking female or ambiguous. At puberty, the big increase in regular testosterone causes them to develop many male characteristics, like a deepening voice and penis growth.
• Learn More: https://medlineplus.gov/genetics/condition/5-alpha-reductase-deficiency/

Congenital Adrenal Hyperplasia (CAH)

• Prevalence: Classic forms affect ~1 in 15,000 to 1 in 20,000 births. Non-classic forms are much more common.
• Technical Explanation: A group of inherited disorders affecting the adrenal glands. The most common form (21-hydroxylase deficiency) impairs cortisol production, leading to overproduction of adrenal androgens. In individuals with XX chromosomes, this excess androgen exposure before birth causes virilization of external genitalia. Internal organs (ovaries, uterus) are typically female. Requires lifelong hormone management.
• Plain English Summary: CAH affects hormone production in the adrenal glands. In the common type, the body can’t make enough cortisol, leading it to produce too much male-type hormone (androgens). In genetic females (XX), this causes their external genitals to look more masculine at birth, even though they have internal female organs. They need lifelong medication.
• Learn More: https://medlineplus.gov/genetics/condition/congenital-adrenal-hyperplasia/

Swyer Syndrome (XY Gonadal Dysgenesis)

• Prevalence: Affects about 1 in 80,000 births.
• Technical Explanation: Individuals have XY chromosomes, but the gonads fail to develop into testes (gonadal dysgenesis), often due to mutations or deletions in the SRY gene. Without testes, no testosterone or Anti-Müllerian Hormone (AMH) is produced. Development follows a female pathway, resulting in female external genitalia, uterus, and fallopian tubes, but non-functional “streak” gonads instead of ovaries. Requires hormone therapy for puberty.
• Plain English Summary: People with Swyer Syndrome are genetically male (XY), but the gene that tells the body to develop testes doesn’t work. Without testes, they develop external female genitals and internal structures like a uterus, but have non-working streak gonads instead of ovaries. They appear female but need hormones to go through puberty.
• Learn More: https://medlineplus.gov/genetics/condition/swyer-syndrome/

46,XX Testicular DSD (XX Male Syndrome)

• Prevalence: Affects about 1 in 20,000 individuals assigned male at birth.
• Technical Explanation: Individuals have XX chromosomes but develop testes and a male phenotype. This usually occurs because the SRY gene has abnormally translocated from the Y chromosome onto one of the X chromosomes during sperm formation in the father. The presence of SRY triggers testis development. Individuals typically appear male but are infertile and may have small testes.
• Plain English Summary: These individuals are genetically female (XX) but appear male. This happens because the key male-determining gene (SRY), normally on the Y chromosome, accidentally moves onto an X chromosome. This gene tells the body to develop testes, leading to a male appearance, though they are usually infertile.
• Learn More: https://medlineplus.gov/genetics/condition/46xx-testicular-difference-of-sex-development/

Persistent Müllerian Duct Syndrome (PMDS)

• Prevalence: Very rare.
• Technical Explanation: Individuals have XY chromosomes, testes, and typical male external genitalia. However, they also retain Müllerian structures (uterus, fallopian tubes) because Anti-Müllerian Hormone (AMH) is either deficient or the body cannot respond to it. AMH normally causes these structures to regress in male fetal development. Often discovered during surgery for undescended testes.
• Plain English Summary: People with PMDS are genetically male (XY) with typical male external parts. However, they also have undeveloped female internal organs like a uterus and fallopian tubes, because the hormone that normally gets rid of these structures in males didn’t work properly.
• Learn More: https://medlineplus.gov/genetics/condition/persistent-mullerian-duct-syndrome/

Chimerism (e.g., 46,XX/46,XY)

• Prevalence: Extremely rare.
• Technical Explanation: An individual develops from the fusion of two distinct fertilized eggs (zygotes) with different genetic makeups (e.g., one XX and one XY). The resulting person has populations of both XX and XY cells distributed variably throughout their body tissues. Physical presentation varies widely, potentially including ambiguous genitalia or the presence of both ovarian and testicular tissue (ovotestes).
• Plain English Summary: Chimerism happens when two separate fertilized eggs merge very early in development, essentially creating one person with two sets of DNA. If one egg was XX (female) and the other XY (male), the person has a mix of XX and XY cells. How this looks physically can vary a lot, from appearing typically male or female to having ambiguous features.
• Known Example: Recording artist Taylor Muhl.
• Learn More: https://en.wikipedia.org/wiki/Chimera_(genetics)

Other Concepts: Mosaicism & Ovotestes

• Mosaicism: Similar to chimerism in having different cell lines, but originates from a single fertilized egg after cell division errors (e.g., some cells 45,X, others 46,XX). Effects vary based on which cells are affected.
• Ovotesticular DSD: Presence of both ovarian (egg-producing) and testicular (sperm-producing) tissue in the same person, either combined in one gonad (ovotestis) or separately. Genitalia are often ambiguous.
• Learn More (Ovotesticular DSD): https://medlineplus.gov/genetics/condition/ovotesticular-disorder-of-sex-development/

Biology is a Spectrum, Not Just a Binary

As these examples show, human biological sex isn’t always a straightforward matter of XX or XY. Chromosomes, hormones, and anatomy interact in complex ways, leading to a natural spectrum of development. The simple binary model, while common, doesn’t capture the full reality for everyone.

Biological Variations, Identity, and Personal Choices

The lived experiences of individuals with the biological diversity described above vary greatly. Some people live comfortably aligned with the gender they were assigned at birth, navigating their unique biology within that context. There is no single “intersex experience.”

However, it has also been widely reported that others experience profound feelings that something is ‘different’ or doesn’t quite align – a sense of incongruence. These feelings can be present from a young age and may relate complexly to their specific biological makeup (XY chromosomes with female anatomy, ovotestes, hormonal differences, etc.), their physical body’s function or appearance, their internal sense of self (gender identity), or societal expectations and pressures. Deep biological impulses and instincts likely play a significant role in these internal experiences.

To sneak in one other story… here’s a woman born with two vaginas, two cervices and two uteri:

When you look at all of these variations, you can imagine that when faced with these kinds of incongruence – perhaps being born with ovotestes, or having XY chromosomes but female anatomy (like CAIS), or XX chromosomes with virilized genitalia (like CAH) – choosing medical interventions like hormone therapy or reconstructive/affirming surgery becomes a deeply personal decision, and a rational consideration for some. This isn’t about rejecting biology, but about seeking alignment and well-being within their own biological reality. The goals are often to:

• Align their physical body more closely with their experienced gender identity.
• Improve physical function or address medical needs related to their specific anatomy.
• Alleviate significant distress (gender dysphoria) caused by the incongruence stemming directly from their specific biological development and lived experience.

This is a journey unique to each individual navigating their reality.

Embracing Complexity Beyond the Binary

Acknowledging the reality of biological diversity is the first step toward a more accurate and compassionate understanding of human sex and gender. The simple XX/XY binary doesn’t tell the whole story. Variations are natural, and the experiences of individuals with these variations – whether they feel aligned with their assigned sex or experience incongruence – are valid.

Ultimately, whether a person with a biological variation decides to embrace the gender assigned at birth, or take medical steps to better align their body and identity based on what feels correct for them, is their decision alone. It is a path forged from a unique lived experience – navigating feelings, instincts, and a biological reality that the vast majority of people (the 98%+ with typical biological development) cannot fully comprehend.

Therefore, judgment and stigma have no place when discussing these personal choices. Moving beyond oversimplified views allows for a more accurate understanding and fosters the empathy and respect everyone deserves, regardless of where they fall on the broad and natural spectrum of human development.

Bottom Line

Religious hardliners love the slogan “everyone is either a man or a woman, period.” They treat that as a divine law, then use it to justify stripping civil rights from anyone who does not fit their categories.

The problem is simple. Biology has already documented real humans who do not fit cleanly into “male” or “female” by chromosomes, gonads, hormones, or anatomy. One such person would be enough to falsify their absolute claim. We have an entire catalog of them.

On top of that, bodily autonomy does not require anyone’s permission. If an adult wants to change their body, that is their right, whether their chromosomes are “normal” or not. In cases where someone is born with atypical sex traits and a deep mismatch between their body and their sense of self, transitioning is not rebellion against nature. It is an attempt to correct a developmental error and reduce suffering.