Quote Originally Posted by BirdofHermes View Post
You misunderstand me, I did not mean three generations in Aragorn's line (which would not make a difference in the 42 generations of his ancestors since Elros), but in Arwen's.
Oh, I see what you mean now

Thing is, Arwen had obviously turned out okay (and then some), and apparently genetically speaking a bit of inbreeding does little harm and may even do some good (because some shared traits can be beneficial), so there you go. Doesn't exactly come recommended but it seems you can get away with it... up to a point.