Indeed, Genetically Superior....for WHAT?
Life is about survival and breeding. for example, a lot of people of white background have better genes to fight off Smallpox, plague, measles, and other illnesses that struck europe over the years, as those who survived had children. Other groups, such as the natives of North and South America and Africa, did not have such illnesses, and thus in some cases where devastated by these illnesses once exposed to it, (under some estimates, Smallpox and measles killed off 95% of the native populations of North and south america, and is now circled as the reason why the Mississippi culture died) However many African's and those of African background who ancestors have dealt with malaria for generations have become resistant or immune to it, while a European would be much more prone to getting deathly ill over it. (In fact, Sickle Cell anima comes from a mutation that became common as it carriers are resistant/immune to Malaria (I think it Immune, but I can be wrong), but if you have two copies of the gene, you have a hard time getting enough oxygen in the bloodstream.
Or as a "What-if" example, if HIV had gone airborn before the drug cocktail that lets people live with HIV, and everyone was infected, there would be some people who would live, as some European and Asians are immune to HIV, (They think its related to a specific plague resistance) and these people would live on and have kids and humanity would go on. however if there was a "Super-malaria" that infected and killed everyone that was not immune to it, there would be africans who would live.
The key thing is to have enough genetic diversity so that no one illness or predator takes out your entire population.