Reddit mentions of Migrating Genders: Westernisation, Migration, and Samoan Fa'afafine (Anthropology and Cultural History in Asia and the Indo-Pacific)

OK, let's test it. "There are more than two genders in some cultures" is our hypothesis.

Here, the result. https://en.wikipedia.org/wiki/Fa%27afafine

Fa'afafine are people who identify themselves as a third-gender in Samoa, American Samoa and the Samoan diaspora. A recognized gender identity/gender role since at least the early 20th century in Samoan society, and some theorize an integral part of traditional Samoan culture, fa'afafine are assigned male at birth, and explicitly embody both masculine and feminine gender traits, fashioned in a way unique to this part of the world. Their behavior typically ranges from extravagantly feminine to conventionally masculine.

Here, some images of people identifying as this third gender: https://www.google.se/search?q=Fa%27afafine&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi29dSovZXUAhVnL8AKHQCcAdIQ_AUIBigB&biw=1920&bih=950

A Vice documentary describing this third gender: https://www.youtube.com/watch?v=F9xvkCa63Js

A cultural event with these third gender people present: http://www.bbc.com/news/world-asia-37227803

Some scientific articles discussing the gender: https://www.amazon.com/Migrating-Genders-Westernisation-Anthropology-Indo-Pacific/dp/1409402738

http://hawaii.universitypressscholarship.com/view/10.21313/hawaii/9780824838829.001.0001/upso-9780824838829-chapter-004

http://people.wku.edu/barry.kaufkins/280/THE%20ISLANDS%20WHERE%20BOYS%20GROW%20UP%20TO%20BE%20GIRLS.htm

I daresay I have proven to you that these people exist.