Your gender is pre determined prior to your actual birth by genetic code. Evolution has created for humans two genders: make and female. Males are generally more dominant, aggressive, intelligent, and indisputably stronger. Female are more inclined to passive duites, less aggressive, less intelligent, and organically weaker (even with physical training they will never match a man with the same degree of training).
People only doubt their gender and their responsibilities of that gender when they become indoctrinated with liberal idiocy that promotes this. Testosterone is what makes a man feel like a man and if it is missing in the body, the male may begin feeling effete and then lose his identity and start acting like the female he "thinks" he is.
Same goes with estrogen. If females lose estrogen or don't have supple quantities in then, they will become/feel less female like and try acting like men (yes both genders ACT DIFFERENT).
In a word, it is a mental and biological issue and defect that shouldn't be celebrated or promoted: it is like me promoting cancer and saying that it needs to be left untreated since it is "natural".