I started reading these books back in 1968 or 69. I already knew who I was; a transsexual. Benjamin's book came out in 1966, Then Robert Stoller was next in 1968 and Green and Money in 1969. Those were the first "BIG FOUR" in the field; I think after Benjamin, who advocated biological determinants, is where the wheels started coming off the bus, slowly at first and then it took a radical wrong turn with Money, which is a very strange story.
With Stoller, the etiology of transsexual being due to a psychoanalytic disturbance began to creep into the discussion. Psychoanalytic theory or Object Relations as it is more often practiced today, views us as deeply disturbed, severely personality disordered and deviant. You do not see that kind of language with Benjamin, except in the sense that it is an anomalous, statistically significant rarity. Psychoanalytic theory blames the maternal relationship for just about every problem under the sun from schizophrenia to transsexualism and all sorts of other mental maladies. Psychoanalytic theory is based on mythology and that the powers of myths describe human conflicts which are why Psychoanalysis is such an arcane practice. We do have to note that the Greek and Roman mythology was created as an explanation of human behavior which makes psychoanalysis of value.
Things get worse with John Money, a Feminist. He fully ascribed to Social Learning theory of personality development and this is where feminism chimes in. They believed in John Locke's idea of Tabula Rasa: the mind is a blank slate and you can take a baby regardless of biological potential and raise it to be anything, doctor, banker, lawyer, male, female, whatever; all by environmental determinations. Biology plays no role in this and there is Money's infamous destruction of one child's life that he had recommended to reassigned female after a terribly tragic circumcision accident that destroyed his penis. That was passed off as a great success for so many years until the truth came out after that poor person suicided. Money advocated the promotion of pornography and suggested that pedophilia was not necessarily an unhealthy practice.
Feminists believe the same thing about social learning as did Money. They believe that much of feminine behavior is societally enforced through a coercive patriarchy. They believe that women who are traditionally feminine and take more traditional roles are sell outs to the patriarchy.
There is a hierarchy of science: Physics, Chemistry, biology, Psychology and Sociology, Economics and Political science. You can see where things stand from that hierarchy. Psychoanalysis tends to be a blend of psychology and sociological theory.
BTW, 1:500 males have Klinefelter's mosaic which a portion of cells are XY and a portion of cells are XXY in various proportions. This is usually discovered in men who are infertile and they have a higher rate of transsexualism than XY males. Of course there are the more severe cases of Andorgen Insensitivity Disorder, Congenital Adrenal Hyperplasia and questions about other more subtle brain changes due to hormonal washing at different times in life.
As we become more sophisticated in neurophysiology, I think more will be learned that Transsexualism is by and large a biological condition and not as a result of any social learning theory.