You’ve probably heard the red hair comparison. It’s the go-to factoid in almost every conversation about human biology these days. People love to say that being intersex is "just as common as having red hair." It’s a catchy line. It makes a complex biological reality feel instantly relatable. But if you actually start digging into the medical charts and the decades of academic bickering, you’ll find that the answer to what percentage of people are intersex isn’t just one single number. It’s a range that depends entirely on who you ask and how they define "normal."
Biology is messy.
Most of us were taught in grade school that there are two boxes: male and female. You get one or the other. But for millions of people, the body doesn't follow that exact script. Maybe the chromosomes are different, or the hormone receptors don't respond the way they "should," or the internal organs don't match the external ones. When these variations happen, we use the umbrella term intersex.
The Famous 1.7% Figure: Where Did It Come From?
If you Google this topic, the number 1.7% pops up everywhere. It’s in United Nations reports, Amnesty International briefings, and countless viral TikToks.
This specific statistic comes from a massive review of medical literature conducted by Dr. Anne Fausto-Sterling and her team at Brown University back in 2000. They looked at nearly 50 years of data to see how many people "deviated from the Platonic ideal" of male or female.
Their finding? About 1.7 out of every 100 births involve some form of intersex trait.
To put that in perspective, if you’re in a crowded stadium with 50,000 people, roughly 850 of them would be intersex according to this math. That’s a lot of people. It’s why the "red hair" analogy (which also sits around 1–2% globally) became so popular. It proves that intersex people aren't some one-in-a-million anomaly; they are part of the standard variety of human life.
Why Some Experts Think 1.7% Is Way Too High
Honestly, not everyone in the medical community agrees with Fausto-Sterling. Shortly after her research was published, Dr. Leonard Sax—a physician and psychologist—published a pretty famous rebuttal.
Sax argued that the 1.7% figure is misleading because it includes conditions that don't actually result in "ambiguous" sex characteristics. For example, he pointed out that Late-Onset Congenital Adrenal Hyperplasia (LOCAH) makes up the vast majority of that 1.7%.
People with LOCAH usually look like typical males or females at birth. They might not even know they have a variation until they hit puberty and deal with things like severe acne or irregular periods.
Sax's take? If you only count people whose bodies are physically, visibly "in-between" at birth—or those whose chromosomes don't match their anatomy—the number drops to about 0.018%.
That is a massive difference. We are talking about the difference between 1 in 60 people and 1 in 5,500 people.
The Reality Lives in the Nuance
So, who’s right? It kind of depends on why you're asking.
If you are a doctor looking at clinical "Disorders of Sex Development" (DSD), you might prefer a narrower definition. But if you are a sociologist or a human rights advocate, you’re likely looking at the broader spectrum of biological diversity.
The 1.7% figure isn't "fake," but it is broad. It includes:
- Klinefelter Syndrome (XXY): About 1 in 500 to 1,000 births.
- Turner Syndrome (X0): About 1 in 2,500 births.
- Androgen Insensitivity Syndrome: Where an XY body doesn't respond to male hormones.
- MRKH: Where a person is born without a uterus.
Some of these people will live their whole lives never knowing they are intersex. Others will have surgeries performed on them as infants to make their bodies fit a binary norm—a practice that many intersex activists, like those at InterACT, are fighting to end.
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Real World Data from 2024 and 2025
Recent surveys are starting to give us a better "boots on the ground" look at these numbers. For instance, a 2024 survey by The Trevor Project found that about 1.4% of LGBTQ+ youth identified as intersex.
In Mexico, a huge study published in PNAS Nexus (2024/2025) looked at over 44,000 people and found that 1.6% of the population aged 15–64 reported intersex variations. This study was particularly important because it didn't just look at chromosomes in a lab; it looked at how people actually live. It found that intersex folks often face much higher rates of bullying and healthcare discrimination.
What Most People Get Wrong
The biggest misconception is that "intersex" is a third gender. It’s not.
Most intersex people identify as either men or women. Being intersex is about your biological traits, not your gender identity or who you’re attracted to. You can be an intersex man, an intersex woman, or non-binary.
Another myth is that you can always "tell" by looking. You can't. You’ve probably walked past dozens of intersex people this week and had zero clue.
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Actionable Insights: What You Can Do Now
If you’re trying to be a better ally or just want to understand the biology better, here’s how to handle this information:
- Stop using "hermaphrodite." It’s considered outdated and often offensive. "Intersex" is the accepted term.
- Acknowledge the range. When talking about what percentage of people are intersex, mention that while 1.7% is the most common estimate for all variations, about 1 in 2,000 babies are born with traits that lead to immediate clinical attention.
- Support bodily autonomy. The biggest issue for the intersex community right now isn't just "being counted"—it's the right to not have "normalizing" surgeries until they are old enough to consent for themselves.
- Listen to intersex voices. Follow creators and advocates like Pidgeon Pagonis or organizations like Intersex Campaign for Equality. They provide the lived experience that a math equation can't capture.
The bottom line is that humans are more diverse than a binary "A or B" choice. Whether the number is 1.7% or 0.018%, these are real people with real lives who deserve to have their biology respected rather than "corrected."
To learn more about the specific conditions under the intersex umbrella, you should look into the clinical definitions of "Differences of Sex Development" (DSD) provided by major health organizations like the Mayo Clinic or the NHS. Understanding the specific biology of conditions like CAH or AIS helps move the conversation from abstract percentages to tangible human experiences.