What a shame it would be if we lost the wonderful differences among us. Diversity is good, variety is beautiful. If we all looked the same, why would we even bother looking at each other?
The whole idea, of course, is absurd anyway. No, dark skin is not a more dominant gene than light skin. As explained in greater detail at http://www.redprince.net/genlab/, skin color is polygenic. There is not one but three genes that determine the skin color. And since genes actually come in pairs, there are six "bits" of genetic information which determine the skin color.
As in computers, each "bit" is either on or off. On meaning "dark", off meaning "light" in this case. Unlike in computers, the polygenic "bits" are simply added up. If they are all off, the sum is 0. If they are all on, the sum is 6. That gives us seven possible sums (0-6).
If your sum is 0, your skin will be very light, if it is 6, it will be very dark.
That means that forceful crossbreeding would not result in all of us being the same color. Suppose, you somehow manage to get everyone's skin color to become genetically coded as 3 (that is the average on the scale of 0 - 6). Now, in some cases it will mean one gene pair of 2, one of 1, one of 0. In other cases, it will mean three gene pairs of 1.
Either way, when these people breed, they will have children some of whom are light skinned, some of whom are dark skinned. Indeed, if both parents have three gene pairs of 1, it is possible for them to have one child of 0 (completely light) when both parents pass three zeros, and another child of 6 (completely dark), when both parents pass three ones.
All in all, we are lucky: Our genetic system is designed to prevent any politically correct madman to prevent the destruction of our diversity. Thank goodness for that! | 
