According to Facebook’s official announcement, “We collaborated with our Network of Support, a group of leading LGBT advocacy organizations, to offer an extensive list of gender identities that many people use to describe themselves. Moreover, people who select a custom gender will now have the ability to choose the pronoun they’d like to be referred to publicly — male (he/his), female (she/her) or neutral (they/their).” Facebook also stated that this new custom gender option can be hidden from people they might not want to share it with, such as co-workers, friends, family members, and so on.
The list of identities is pretty extensive and if you’d like to see them all, hit up ReadWrite’s website for the details. We’re not sure if this is the entire list because according to ReadWrite, they identified it by using the autocomplete drop-down menu, so there could be more that has yet to be identified.