I have always discussed things like this with my children with no harm and it has meant that now they are adults, as far as they are concerned, people are people and their gender, sexuality, disability status etc, is just a part of them and they accept and do not 'fear' it. My parents did the same with us, I think mainly because one of their friends after many years of depression and suicide attempts made the decision to transition and they needed to explain to us why all of a sudden he was dressing and living as a female openly...the explanation was far more understandable to us than the confusion caused before the explanation.
With regards to giving drugs to young children, not sure how it is perfectly ok to give drugs to control behaviour (Ritalin etc) which does have a very damaging impact on them when there are other methods available but not ok to merely pause puberty until the child is mature enough to make their own informed decision.