Gender is a grammatical construct, not a social-cultural-psychological construct.
English only has three genders:
1. masculine
2. feminine
3. neuter
Choose one.
That was true, until about 25 years ago, when it started to become redefined. Today, it’s in dictionaries as a social-cultural-psychological construct. All that means is that it is all in the mind.
The real problem comes from the conflation of “sex” and “gender”. That makes rational discussion of the related topics impossible. If you force “them” to adhere to the (current) definitions; then, you can get somewhere. If “they” say: “there are 27 genders” — simply point out that there are only two sexes.