I just want to remind everyone that the destruction of the Berlin Institute of Sexual Science by the Nazis was a great step backward for all the various people who we consider queer.
Also it's interesting in Europe that in the early 1900s, bisexuality referred to a theory about sex not orientation (as we currently understand those concepts). The theory proposed that "maleness" and "femaleness" were somewhat like substances that were mixed in different proportions to produce men and women, but that everyone contained some portion of the other "sex".
This theory made conceiving of the deliberate transformation of a person from one sex to another easier. In Europe where this theory was popular they were far more willing to experiment with sex reassignment techniques than their American counterparts who adhered to a more binary theory of sex.