There are multiple genders. There always have been. Nobody ever manages to actually refute this, and people who try generally end up resorting to insults.
this is the problem. People can think or identify as what they like. But you can’t force other people to accept what they say of themselves is true.
and there haven’t always been “multiple genders”. When I was growing up (I’m 50) no one was trans or NB. There were men, women and transsexuals who had undergone a sex change (usually older men). Transvestites ie men who were still men but wore women’s clothes. No “multiple genders”.
and a teenage human identifying as a cat is crazy. Could those kids have expressed that better yes but they are 13. Aren’t we always being told that their young brains are still developing? I’d express it more politely at 50, but cat kid would be left in no doubt that I did not accept their identity as valid and would not be going along with it.