Cut to the scene where Vader reveals the truth to Luke in Empire Strikes Back.
Darth Vader: Turn to the dark side, and join me.
Luke Skywalker: I'll never join you! You killed my father!
Vader: No, Luke. I am your father.
Luke: That's not true! That's impossible!
Vader: And Princess Leah is your sister.
Luke: That's not true! That's...improbable.
Vader: And the Empire will be defeated by Ewoks!
Luke: That's...chk...very unlikely.
Vader: And as a child, I built C3-PO!
(Vader is sipping tea and Luke is smoking a cigarette)
Vader: And the force? Well, that's just microscopic bacteria in your bloodstream called midi-chlorians.
Luke: Look, if you're not going to take this seriously, I'm out. (walks away safely)