Chad: That's a very good point. Ns think it's cleared up then that Darth Vader didn't know Leia also existed before ROTJ, but Yoda's quote "No. Over there is another" has constantly confused me. One of two people in ESB the was already known that Leia would certainly be revealed as Luke's sister, or they're talking about someone else. I uncover the prior to be more believable.
No.At that suggest he doesn"t also know Luke is his son and that"s what starts his attention in detect "Young Skywalker."
You are watching: Did vader know leia was his daughter
He shows his surprise at finding out that Luke has a sister in Return the the Jedi once he states he watch Luke"s feel are strong for his girlfriend – then adds, in surprise, "Sister."
Wookieepedia says (when explicate the duel in between Luke and also Vader ~ above the new Death Star):
Vader, who had actually been probing Luke"s thoughts, discovered that besides Luke he also had a daughter: Leia Organa
However, no attribution for this delinquent is offered in the article.
To re-use component of mine answer come an unrelated inquiry Why perform we hear Leia's Theme during Kenobi's death?:
At the time of working of "A new Hope" (e.g. Before 1977) - it to be NOT recognized to anyone (including Lucas) the Luke and also Leia room family. Since Luke was Anakin Skywalker"s kid from the start of ANH, that means Leia wasn"t supposed to be his daughter, until at least mid-work on illustration V.
See more: Geometry: How Many Faces Does A Sphere Have A Face, Geometry: How Many Faces Does A Sphere Have
To be more specific, even very early Leigh Brackett"s 1978 breeze of "The realm Strikes Back" didn"t have that relationship established yet - the was presented later (source).
Another related proof for Luke and Leia no yet being related was 1978 pre-ESB book that to be a sequel come "ANH" - Alan Dean Foster"s "Splinter that the Mind"s Eye". It establishes the theme of romantic interest between the two (presumably, in part, because Foster and also Lucas didn"t understand if ANH would be a huge hit and if Harrison Ford would certainly be interested in the sequel should the sequel be based upon "Splinter")