Humankind is uncomfortable with that are deemed unfamiliar, outside the so-called norm, & uncertainty. People welcome, even love the familiar. The familiar makes people comfortable, safe, & relaxed. The familiar makes people sure. People want to associate w/others who are like them. Also, people love defined boundaries.
On that subject, people are comfortable w/defined, delineated gender boundaries. With such defined, delineated gender boundaries, such has a place. The gender lines in such minds are clear & succinct. However, people are very uncomfortable when gender lines & roles are blurred. That is why many people get into histrionics regarding the issue of homosexuality, androgyny, & transgenderism. Such categories are viewed as outside the norm for many people hence they become quite unnerved at the issue of so-called blurred sexual identities.
What they don't acknowledge that humankind is naturally bisexual but because of familial, religious, & societal inculcations, must suppress their inclinations to conform to the prevailing familial, religious, & societal construct. The same w/homosexuality, androgyny, & transgenderism, such are a normal part of the human condition but because of familial, religious, & societal dictates, these factions of human sexuality has been ostracized, even demonized & marginalized.
People want things that they can easily defined & delineated. This is elementary consciousness & thinking. The thought of people being outside defined sexual boundaries is beyond perplexing to such elementary minds. Evolved, mature people know that there are people are beyond rigid societal definitions of what gender is. This is the 21st century when gender lines are being constantly blurred & the age of strictly defined gender in its functions & roles are becoming outmoded.