Children often ask their parents questions that are difficult to answer. One such common question is "Why is my skin light, but yours is dark?"
The answer begins with the stars.
Everyone knows that Coyote is mischievous. When he and the world were young, Coyote saw Spider pushing the Sun up a hill. Coyote thought it was a game, so he ran over and knocked the Sun back down. Then the sky became dark. Spider was angry, because now he would have to go back down to get the Sun again. Coyote laughed, "Kekeke!"
Not seeing any more fun to be had with Spider, Coyote ran around in the dark until he found a brightly lit pond. He jumped in, but being young, the cold water surprised him. So he ran away from it, but the bright water was still on him. When he shook the water off, it landed in the sky, creating the stars.
Before long, Spider had pushed the Sun back up into the sky. Feeling braver in the warm Sun, Coyote walked back to the pond. The brightness was gone, but it was now filled with colors. He jumped all the way in, and splashed around. It was fun, but he became lonely. After shaking the water off, the colors landed all over the world.
Then he went to where the first people were. He convinced them to follow him to the pond, and swim with him. Some of them did, but some did not. The ones who did were soon covered in the colorful water.
That's why to this day, some children have blue or green eyes, and some have brown eyes. Some children have pink skin, while their parents might be as dark as coal. Some children have yellow or red hair, but their brothers and sisters might have black or brown hair.
As far as anyone can tell, the story must be true, because the appearance a person is born with is totally random, and seems to have nothing to do with what their parents look like. Some cultivators could change their appearance, depending on their cultivation technique or their constitution, but for mortals, there was no significance to skin, hair, or eye color.