mrsgreenfinger, there have been numerous threads on this forum discussing the question you raise. You can find them by asking in the search box above.
The issue of the age at which children begin to feel they’re in the wrong body so far as gender is concerned is contentious. For what it’s worth I find it difficult to believe an 18 month old is able to make that distinction. My now 6 year old grandson spent the period from 3 - 4 dressed as Moana, his favourite Disney character. He’s 6 now and as I’d expect developmentally curious about his gender on so many levels. He has twin uncles, one heterosexual, married with a child. The other twin is gay, married with a child.
My 2 year old grandson loves princesses, loves frozen and wears his 3 year old (female) cousin’s Frozen frock.
None of this is unusual.
Going on the telly to enjoy your 15 minutes of fame whilst exploiting your 4 year old, that’s cruel and unusual. We know much more now about sexual preferences, gender issues than we did 50 years ago. Lets celebrate that and continue to learn, without exploiting our children