The way the non-binary faithful obsess about intersexes, and about individuals who can’t produce gametes, amounts to a pathetic clutching at straws while they drown in postmodern effluent. Yes, some fish change from sperm-producing male to egg-producing female (or vice versa). That very statement relies on the gametic definition of male & female. Ditto hermaphroditic worms & snails who can produce both male & female gametes.
In any case, the existence of intersexes is irrelevant to transexualist claims, since trans people don’t claim to be intersexes. Also, as if it matters, humans are not worms, snails, or fish.
The rare tetra-amelia syndrome (babies born without limbs) does not negate the statement that Homo sapiens is a bipedal species. The rare four-winged bithorax mutation does not negate the statement that Drosophila is a Dipteran (two winged) fly. Similarly, the occasional individual who can’t produce gametes doesn’t negate the generalisation that mammals come in only two sexes, male and female, defined by games size.
Sex is binary as a matter of biological fact. "Gender" is a different matter and I leave that to others to define.
https://twitter.com/RichardDawkins/status/1753045097959100600
Very nice image in the comment thread.