I’d argue talking about how babies are made with mommy and daddy is just as appropriate or inappropriate as talking about changing sex, depending on the age, occasion and intent.

Changing ‘Gender’ without deviating sexually however should be fine imho… I’m a straight male and I have never shunned anybody for what they think or believe, many of which were very different than my experience of life or personal belief. If I can’t relate I just accept, and I don’t think any information about genderfluidity would have changed me, but instead maybe even better educated me to know how to respect others that are cause I’ve been in quite a few arguments about it just for being uninformed about something that didn’t apply to me. It’s harder than it should be to ask “why” for reasoning and clarification as a binary without apparently sounding condescendent, so advance information about it would have actually been helpful to me… 😅