When we were young I suspect a lot of us underestimated the number of homosexual people in the population as sexual relations between men were illegal and so homosexual men had, in the main, to keep their private lives very private.
Thinking back, nobody really discussed lesbians, but there seemed to be quite a number of single women, including a number of teachers at our all-girls school, who lived together as pairs. We tended to put this down to having lost their fiance/boyfriend in the war, which of course might have been true in some cases.
Fast forward fifty years and I guess that most of us now have friends or family in same sex relationships. It seems quite unremarkable.
I can only think of a very small number of transgender people I have actually come across, as opposed to reading about. One is a young man, born a little girl, who expressed a strong wish to become a boy from the time she was able to speak.
I suspect that if we fast forward another fifty years (most of us won't be around to see it) there may be many more transgender people and again that will have become unremarkable.