Considering the fact that gender identification may extend to biological as well and mental issues, a lone psychologist is not enough. You need a consensus of psychiatry and psychology.
Anything other than that is merely an uninformed or partially informed opinion.
The fact of the matter is this subject is still being studied. The world's greatest experts have not yet reached a consensus. So who the fuck is anyone on this board to make any determination at all?
Dunning Kruger.
So your stance is that we dont know if its 100% nature, society, or even a mixture. That still means that any statement that its 100% anything is wrong. That said, here is this.
http://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(16)30310-8/fulltext
Finally, there is the question of gender. This refers to the social aspects or construct of a person, how they perceive themselves and how others perceive them. Gender is usually expressed as a binary (female/male) factor but can be regarded as a spectrum, with multiple ways for individuals to identify themselves, often grouped under the term non-binary. For many fields of medical research, gender might not be influential, but in psychiatry it matters. Mental health is above all about how a person thinks and feels. That reflects their biological health but also their sense of self, how they think that others perceive and treat them, and how they see their role in society. The role of sex and gender clearly needs to be acknowledged; and researchers should also be aware of their own preconceptions, and how these might affect both the scientific questions they ask, and their interpretation of the data they collect.
So enjoy a paper from "The Lancet Psychiatry".
