The latest round in the gender wars is amusing to me as a gun owner. It seems the ATF will accept non-gender-specific ID documents, but the applicant for a background check must still identify their sex as male or female.
Neither statute nor regulation require the identification document contain the person’s sex. Therefore, identification documents issued with binary, non-binary, or no sex designation may be used as an identification document. For example, a military identification card is a valid identification document and does not contain a sex or gender; see ATF Ruling 2001-5. Accordingly, as long as licensees verify the identity of the transferee by examining a valid transferee identification document then they will be in compliance with the GCA at 922(t)(1)(C).
. . .
The regulations pertaining to the National Instant Criminal Background Check System (NICS) at 28 CFR 25.7 require the sex of the transferee in order to conduct a firearms background check. This information is captured on the ATF Form 4473, question #6, which requires the transferee to indicate his/her sex (not gender) by checking or filling in the applicable box adjacent to “Male” or “Female”. Transferees must select either “Male” or “Female”, but cannot choose both or write in “X” regardless of what is recorded on the transferee’s identification document. If the transferee refuses to complete question #6 then the FFL may not transfer the firearm.
There's more at the link. Bold, underlined text is my emphasis.
Given that Facebook recognizes up to 71 gender options, I can see this causing some . . . friction, to put it mildly. Just for instance: if you consider yourself an oyster on the half shell, given that oysters can change their sex (more than once) during their lives, does that make you ineligible to own a gun? That might en-gender a certain bitterness (you should pardon the expression) . . . In that case, I'm not going to give you one of mine. I intend to be shellfish about it.