The Fallacy of Immutable “Biological Sex”

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1/18: An editorial on sex & gender in @bmj_latest. The editorial is behind a paywall, but there are two “rapid responses” that capture ends of this “debate.” I encourage reading all three if you can. bmj.com/content/372/bmj.n735

2/18: The categorization of people into binary, immutable sexes at birth based on "biological factors" is as much of a “construct” as gender is.

3/18: Although we've been doing it for ages, there is no accepted formula for translating biological characteristics into a binary M/F designation. Any attempt at creating one immediately generates exceptions, which cannot occur in a binary system.

4/18: Nearly all the factors on which we base binary sex determination can be changed, and for myriad reasons not limited to gender-affirming care. Claims that "biological sex" is binary, set at birth and thereafter immutable are false.

5/18: How can the categorization be unchangeable when virtually all the variables from which it’s comprised can be altered? There isn’t even an agreed-upon list of variables or whether they are categorical, continuous or both.

6/18: The imperative for trans-exclusionary groups to validate an immutable, binary sex designation at birth is clear. Without it, they have no “scientific” leg on which to prop a sex-based ideology.

7/18: But in medicine, what do we gain from using the ambiguous term "sex" rather than “gender” and the *specific* biological characteristics that apparently inform a “sex” designation?

8/18: “It is long overdue,” wrote @Karkazis, “that we understand sex not as an essential property of individuals but as a set of biological traits and social factors that become important only in specific contexts...and even then complexity persists.” sciencedirect.com/science/article/pii/S0140673619327643

9/18: ”If we are concerned with certain cancers...knowing whether someone has a prostate or ovaries is what’s important, not their 'sex' per see." @Karkazis

10/18: Recent research suggests that gender-affirming hormonal treatment in transgender people altered lipid profiles and the risk of general and hard CVD events. (Sig. increase in trans men & numerical decrease in trans women). @jsexmed sciencedirect.com/science/article/pii/S1743609521002344?via%3Dihub

11/18: If “sex” were indeed a set-in-stone property assigned at birth, using it to accord ASCVD risk could be misleading. Using gender could too, but in combination with the patient’s hormonal milieu, might yield more predictive results.

12/18: Clinical trials often report sex-based subgroup results, and the #ICMJE says to use the term "sex (when reporting biological factors)." icmje.org/recommendations/browse/manuscript-preparation/preparing-for-submission.html.

13/18: However, researchers almost invariably base these claims on data containing physician- or self-report. They use gender as a surrogate for sex and then sex, in turn, as a proxy for "biological factors.”

14/18: But why not just report the actual biological factors assessed? Surely, that would be more precise than reporting results based on “biological factors.”

15/18: And if no actual “biological factors” are assessed, then use “gender.” It shouldn’t be sufficient to claim that a finding differs between genders because of “biological factors” without showing that the specific biological factors at issue actually drive the difference.

16/18: It might seem to researchers, readers and editors that biological factors must be responsible for a difference, but if data are based on gender, then what’s been shown, and what should be reported, is a gender-based difference.

17/18 To return to @Karkazis: “For those arenas where it’s not clear what purpose sex designation serves, we might question whether we need it at all. Doing so could lead to better science and health care, and, crucially, less harm.”

18/18: I would suggest that medicine and the science of humans is one such arena. It’s time to treat “sex” as an antiquated and imprecise term whose dominion has long since run its course. It’s being misused to exclude people and science shouldn’t tolerate that.