"HOW USING ‘THEY’ AS A SINGULAR PRONOUN CAN CHANGE THE WORLD"

"Since long before it started being adopted by trans communities, people have used singular they to refer to a hypothetical person whose gender is unknown. It’s especially common in reference to a noun that is syntactically singular but logically plural, like “someone,” “anyone,” and “whoever.” We say things like, “Someone left their umbrella in the meeting room.” We could say, “Someone left his or her umbrella,” but using “their” is more common, easier to understand, and not wrong. Published examples of this usage abound, from as early as Chaucer through the present day.

The rule against using singular they is enforced neither because it preserves some consistent, objective grammatical standard, nor because it serves our communication needs. It is enforced because enforcing language norms is a way of enforcing power structures. Our pronoun problem isn’t just about gender — it’s about power...

People with non-binary gender identities continually face situations in which someone feels “forced,” by the language norms they’ve internalized, to call us either he or she — even if they’re not sure which one is right, and sometimes even if they have been told that neither is right. These moments, which seem to be about grammar rules, highlight a gender rule that doesn’t work for us: the rule that everyone must be either a he or a she, a man or a woman; that there are no non-binary genders."

http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/

Includes an interesting linguistic history of you coming to be both singular and plural.

I was in a weekly discussion group once that gave itself the interesting challenge to only use gender when it was absolutely, irrevocably relevent to what was being said - for example, when telling a story about my brother I would say 'my sibling' except when it was relevant that he was male. This was an especially interesting task when discussing parents - I realize all the background assumptions that are communicated by starting with 'my mom is always...' versus 'my dad is always...' or whatever. There was a lot of use of the singular they, and pulling gender out both made clearer points and forced the speaker to say out loud what they wanted us to assume about the subject of their stories - it also was interesting to realize when I was making assumptions about gender, and what those assumptions were based on, and how often they turned out to be incorrect.