Wonder Gem PigtailsOfDoom wrote:
Well, and Sith Pureblood is kind of a misnomer too, because the actual Sith race has been watered down significantly over the eons of Sith miscegenation with humans.
I don't think it's meant to say that they are true Sith in relation to the race, they are true Sith in relation to the doctrine in virtue of their blood.
A human can become true Sith, but they aren't born it.
It is the nature of someone with Sith blood, however, to be a true Sith.
The Sith were innately tied to the Dark Side, and the rate of force sensitivity among them was perfect. Any human hybrid with sufficient enough Sith blood to be considered a pureblood (exhibit traits and are strong in the dark side of the force) are nearly always force sensitives.
That's why they likely consider themselves purebloods. Unlike other races, their blood ties them to the dark side of the force innately.
The force is the actual point they care about. They wouldn't consider anyone without the force, even if they had Sith blood, to be a pureblood. And innate alignment to the dark side makes them Sith.
In that sense, it isn't a commentary on purity of genes. Its talking about the distinct features of the true Sith that they cared about--anyone who possesses those is "pure".