Hi @Nick Wallwork9. With the system field of Gender, there are only options for Male/Female. What we've seen other ministries do is disable that field and create a custom field.
There is an enhancement request to edit the system field over in Ideas for Ministry. I would encourage you take a look at voting on. You can easily get to Ideas for Ministry via the blue image on the right side of this page (or through the Support Page in Realm > via the "Share your Feedback" button).