"grow up being their authentic selfs"? so what age would you introduce them to homosexuality and gender theory? would you rather have them be thought that by their school or are you going to teach them that they can just choose their gender or sexuality?
The same age we introduce children to heterosexuality and gender theory. If the information taught is objectively truthful and backed up by scientific discovery then it makes no difference where it's learned because it will be factual.
At what age is it OK to let your kid read a book with a straight couple? At that age is the same age I'd teach for other option to be fine. There's nothing scary about homosexuality just as there isn't for heterosexuality. If them learning about heterosexual relationships doesn't hurt them, learning about homosexual relationships won't hurt them either.