At some point, the first officer man should say, "When I was a little girl ..." and then everyone looks at him funny, and he says, "What, didn't I ever tell you that I'm trans?" Everyone else: "No!" "Oh. Well, now you know."
And then it never gets mentioned again.
"What's trans. Did you mean last week when we.... ohhh... Well we've all spent time as little girls here what is your point?"
Trans doesn't even really make sense in a world where flawless changes to external genitalia/body shape are easy. A more serious show would have characters modified into truly weird alternative sexual patters.
Of course star trek isn't supposed to be serious futurism and who would watch it if they couldn't read their own sexuality into it and ship the characters.