Thread by @FondOfBeetles

I submitted a response at the time.
 
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Correspondence in response to Nature editorial:
 
Gender is a social construct with no scientific definition. The assertion, however, that “processes for deciding sex…[have] no foundation in science” (Nature 563, 5; 2018) is false.

https://twitter.com/Kiwipally/status/1411257447457595402

Mammals are sexually dimorphic, with the male category producing small motile gametes (sperm) for transfer and the female category producing large immotile gametes (ova) and gestating live young.

‘Sex’ is a scientific description of the two qualitatively different reproductive anatomies evolved to fulfil the function of sexual reproduction.

99.98% of people have reproductive anatomies that are unambiguously male or female (Sax J Sex Res 39, 174-8; 2002), regardless of atypical observations of mechanisms which drive sex development, such as “genetic changes”.

However, sex chromosome anomalies detected by basic karyotyping are usually congruent with biological sex. For example, 47, XXY (0.04% of all karyotypes) predicts and successfully drives male sex development (Hamerton Clin Genet. 8, 223-43; 1975).

Some individuals have disorders of sex development (DSDs), although these pathologies are rare and not usually linked to ambiguous biological sex (e.g. Turner syndrome). 0.02% of neonates have external genitalia sufficiently ambiguous to necessitate sex differentiation (Hamerton)

Despite excellent predictive value, it is acknowledged that “genetic testing” alone may be insufficiently rigorous to determine biological sex (due to phenomena such as mosaicism).

Thus, biological sex in these neonates is determined by visualising internal genitalia and gonadal anatomy, supported by genetic analysis and hormone/metabolite profiles.

Reproductive sex development is indeed complex. However, it does not follow that “the research and medical community now sees sex as more complex than male and female”. Based on empirical observation, this complexity does not undermine sexual dimorphism.

Indeed, it is remarkable that despite such molecular and morphological complexity, humans are, except in vanishingly rare cases, unambiguously male or female.

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