Not once did Darth Vader say, "Luke, I am your father." Don't believe me? Proof.
What the masked villain actually said was, "No, I am your father." This is only one of the many things in pop culture history that you think you know… but you don't. You assume "Beam me up, Scotty" came from Star Trek. But not exactly. Was Humpty Dumpty really an egg? Sure, he sat on a wall. Yes, he fell off and got broken. But an egg? It's a mystery. He could have been a fragile glass bottle of Bud Light for all you know.