imperialscum said: The way I see it is that after Great Hyperspace War most of the Sith and Sith-Human hybrid were targeted and killed by the Republic. To fill the void, they just integrated a huge amount of humans from various colonies. So that way the Sith genes were in minority from the beginning. However in one SWTOR missions it is stated that 98% of all imperial population have Sith genetic material. This kind of complicates the upper explanation.

I actually love this idea. I'd say that the surviving Sith and hybrids were so desparate that they breeded with people from their colonies.