Children tend to acquire the average of the skin colors of their parents.
Light and dark skin combined, almost always make an even light brown.
But could you imagine if nobody was tan, and all were dark or pale?
People could make fun of mixed race marriages,
By telling them their kids would “come out tan”.
“Tan” would be a slur. The notion of natural midrange skintones would become a hollering joke.
Or maybe nobody would give a damn.
If you could fuck with the probability of a person’s skin tone according to their genetics,
Race might be treated quite differently.
The same goes for paternity laws.
If you could be even less or more easily identified as belonging to a race,
It would probably just increase and decrease the disharmonies in society.
Things would be quite different, and they’d also be the same.
This is what you get out of a lot of fantasy and sci-fi, a way to show an alternate world based upon our world.
Half of this and half of that,
people seethe to tilt the scale some way.