Most likely, they’d be happy to give you a homo exhibition.
Ya see, that goes straight to the question. You can PROVE you're a girl or boy with paperwork. You can PROVE your ethnic background with paperwork. You can PROVE your marital status with paperwork.
But PROVING that you're gay? Even a homo exhibition only proves you can stick one body part into someone else's body part. Could happen only once. Is that it? POOF! You're gay - forever.
I need more proof than that.