“The preceding words to it too, which make it sound if you can just “choose” your sex, like picking a channel on a television set.”
FWIW and the sake of accuracy, much of the transgender community is not necessarily arguing for a change of sex, because they are arguing it is a change of gender and a separate attribute from biological sex. So, arguments about whether or not biology is involved in transgender are going to be accurate only when they address the issue of whether or not gender and sex are indeed separate attributes.
From the point of view in biology, there are numerous natural examples of fauna which can and do change gender and/or sex with the ability to produce progeny. Consequently, arguments which are critical of transgenderism on the basis of biology must reconcile the natural examples of biological transgenderism to the transgenderism in Humans in order to be persuasive in the biological realm of discussion.
See for one example:
Gender Change in Fish
Unlike mammals the gender or sex of an individual fish is not always fixed from birth. Gender change is considered a form of hermaphrodism, as mentioned on the page on fish reproduction. The change is normally triggered by environmental cues, specifically as a response to the gender of other nearby members of their own species. Most species that undergo gender change live in small schools that are all of one gender except for a single dominant individual, but not all. Anenome fish live as monogamous pairs and in some Gobies the sex ratio is normally 1:1 also.
http://www.earthlife.net/fish/sexchange.html
Hollywood somehow missed making one of those cheap horror movies where the unsuspecting people eat the gender changing fish and find themselves subjected to some very unforeseen consequences.... ;-(
“Consequently, arguments which are critical of transgenderism on the basis of biology must reconcile the natural examples of biological transgenderism to the transgenderism in Humans in order to be persuasive in the biological realm of discussion.”
Humans are not fish or frogs. Point to me spontaneous changes of men into women who can produce offspring, and I’ll pay attention to you.