Worth a second look.
This is an excellent overview of gender diversity, gender non-conforming and non-binary gender identities. The presenter, Justin Dennis, does a good job of explaining the topic. Watch this after watching the USA Today introductionto gender diversity.
Here are resources recommend by Justin:
Nonbinary.org, a wiki-type website with brief definitions: http://nonbinary.org/wiki/Nonbinary
Gender Diversity’s list of terminology: http://www.genderdiversity.org/resources/terminology/
Gender Spectrum’s great explanation of gender, sex, and various other terms: https://www.genderspectrum.org/quick-links/understanding-gender/
Kinsey Confidential’s explanation of gender nonconformity: http://kinseyconfidential.org/gender-nonconformity/
A HuffPo article dispelling myths about gender nonconforming children: http://www.huffingtonpost.com/brynn-tannehill/dispelling-myths-misconceptions-and-lies-about-gender-nonconforming-children_b_5472189.html
An indepth Washington Post article about one agender person and their struggles: http://www.washingtonpost.com/national/when-no-gender-fits-a-quest-to-be-seen-as-just-a-person/2014/09/20/1ab21e6e-2c7b-11e4-994d-202962a9150c_story.html
Wikipedia’s take on the idea of the third gender: http://en.wikipedia.org/wiki/Third_gender
Wikipedia’s article on gender variance, with links to other terms available: http://en.wikipedia.org/wiki/Gender_variance
When girls starting wearing pink and boys started wearing blue: (Hint: more recent than you think) http://www.smithsonianmag.com/arts-culture/when-did-girls-start-wearing-pink-1370097/?no-ist