https://www.bostonglobe.com/ideas/2014/03/09/the-quickly-shifting-language-transgender-community/J0yimos7SoZmVy8mm1Q9LL/story.html
Britt Peterson, Boston Globe

Not long ago, two genders were seen as sufficient for pretty much any form or sign-up page. But as trans or transgender people—umbrella terms encompassing both people who feel at home as members of the opposite sex of their birth, and people who feel their gender can't be reduced to male or female—have become more prominent and more vocal in America, the language is bending to accommodate more possibilities.

This means that more and more Americans, even those who have always taken gender for granted, are reaching for words to talk to and about people in this group in an appropriate way.

Part of the difficulty in adjusting pronouns comes from the rigid, binary nature of English when it comes to gender. "In English you can't refer to an individual in the third person without either gendering them or referring to them with a word that generally connotes lack of humanity—you're either a he or a she or an it," said Susan Stryker, director of the Institute for LGBT Studies at the University of Arizona.