Article published by the BBC claims:

Although there are no reliable statistics on how many Kenyans are intersex, doctors believe the rate is the same as in other countries - about 1.7% of the population. [source]

That seems an awfully high rate. BBC does not cite any sources.

Is this 1.7% figure reliable? (note: the article is about Kenya, but I am interested only in the worldwide figure.

1 Answer 1


The 1.7% figure is from this article[1] (emphasis mine):

Adding the estimates of all known causes of nondimorphic sexual development suggests that approximately 1.7% of all live births do not conform to a Platonic ideal of absolute sex chromosome, gonadal, genital, and hormonal dimorphism.

Another study puts the value around 2% (again emphasis mine):

We surveyed the medical literature from 1955 to the present for studies of the frequency of deviation from the ideal male or female. We conclude that this frequency may be as high as 2% of live births. [2]

The ISNA has a article on how confusing this can be (link) and they don't give out a clear definition, so I won't quote that one.

But in their "10 intersex myths", they state:

In practice, the term “intersex” is used to refer to anybody who was born with anatomy other than what the Powers That Be define as “standard male” or “standard female.”

Note that it only states anatomical differences, while the studies above include other categories.

Other source dispute the broadness of the definitions used by those articles [3] - from their abstract (ellipsis mine, follow previous link for the full text):

(...) Many reviewers are not aware that this figure includes conditions which most clinicians do not recognize as intersex, such as (...) . If the term intersex is to retain any meaning, the term should be restricted to those conditions in which chromosomal sex is inconsistent with phenotypic sex, or in which the phenotype is not classifiable as either male or female. Applying this more precise definition, the true prevalence of intersex is seen to be about 0.018%, almost 100 times lower than Fausto‐Sterling's estimate of 1.7%.

So the 1.7% is valid if you agree with Fausto-Sterling et alia definition of intersex, that is contested as too broad by other authors.

[1] - Blackless, Melanie, Anthony Charuvastra, Amanda Derryck, Anne Fausto-Sterling, Karl Lauzanne, and Ellen Lee. 2000. How sexually dimorphic are we?

[2] - Am. J. Hum. Biol. 12:151–166, 2000. © 2000 Wiley-Liss, Inc. Review and synthesis. American Journal of Human Biology 12:151-166.

[3] - Sax, Leonard: How common is lntersex? A response to Anne Fausto‐Sterling, The Journal of Sex Research Vol. 39 , Iss. 3, 2002 (paywalled)

  • I was googling into references to enrich the question, but I stumbled upon these sources, so I decided to post an answer in tandem. Don't be shy to put up your own answer if you are so inclined. May 22, 2017 at 13:13
  • 3
    Almost all of the 1.7% are from "late-onset CAH". Is there reason to think that is being "born" intersex?
    – DavePhD
    May 22, 2017 at 16:29
  • @DavePhD no idea. From the research linked above, there is no consensus. May 22, 2017 at 17:18
  • 3
    A good ansewer, but I really wish you hadn't skipped over the part of the quote that lists the other things that were included as intersexed. Having a quick list of the things which are included in intersexed definition to reach 1.7% that are not phenotype differences would be quite interesting to me, since 1.7% seemed high to with how I define intersex, my definition of intersex seems to meet the .018% statistic. Now I'm curious about what the difference in definitions is that leads to such a large discrepancy? Are they including people who later identify as trans in the 1.7%?
    – dsollen
    May 23, 2017 at 12:45
  • @dsollen For the sake of brevity the data is left in the articles linked herein; Posting a huge table would not benefit the average reader. The more curious and wary reader could follow the links to find said data. But it seems the data has been partially replicated here: isna.org/faq/frequency May 23, 2017 at 14:09

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