Yes, you need obvious reasons why it would be a secret, and emotional heft and meaning to the reveal, in terms of what it tells us about the characters and their relationships (e.g. Black Sails, where the particular nature of that relationship is the missing piece in how we understand [REDACTED]'s character and backstory).

So it doesn't feel like SHOCK REVEAL: NON-CISHET PEOPLE EXIST! FREAKY! BET YOU NEVER EXPECTED THAT OUTRAGEOUS TWIST!!!