I wish there was a button in settings to disable changing genders in the events tab. There's already a button in each cat's personal tab to do that and I already have headcanons for my cats' gender.
I think the developers have said before they have no plans to create toggles that would remove or prevent trans cats from generating or occurring via events, as it is a harmless gameplay element that you can easily change per-cat in their profile options and the devs are also lgbt or allies to the community.