Just pondering the amount of genetic drift that should occur just by the act of settling new worlds.
So Does Pureblood mean at the point of founding, then natural drift is ok?
Also to consider that the Terran Government established numerous colonies rim ward of Terra in the Interstellar Wars period to build up a population that was Loyal to Terra, in the face of the Vilani's much larger population base. Note at least one of the human client states in this are practiced heavy amounts of human engineering as a matter of state...