Immortality and the sons of Elrond

[Galin]

In 1972 Tolkien appears to make a distinction (letter 345): 'Arwen was not an elf, but one of the half-elven who abandoned her elvish rights.'

To my mind Arwen's satement: 'Do not wonder! for the children of Elrond have the life of the Eldar.' isn't exactly the same thing as simply saying 'we are Elves' (in any case). I think her choice historically echoes that of Luthien (an immortal in any event), in ways similar enough to draw connections, but as WCH notes, Luthien was a unique case.

[Faramir Jones]

We should remember that while Arwen and her brothers had Elrond Halfelven as their father, they had Celebrian, an Elf, as their mother, so were in 'ethnic' terms 75% elvish.