Surely when the MotherFather made us, or brought us into this world, They must have known we would long for Them. I mean, I certainly longed for the sun, even though it hurts me. But They couldn't always be with us, like, physically and all the time. They needed to make sure the swamp, the desert, the mountains, the plains, and the caves are taken care of. The seasons needed to flow one into the other, and that's a big job even for someone as powerful as the MotherFather.
So to keep the first of us safe, the MotherFather collected some of Their essence into several spheres, enough for each of the first of us. Each kin was given their own personal mote, as warm and brilliant as the sun as a sign of their Life within the world.
Which isn't to say that there was no sun at all. There was a sun in the sky, as well as the moon and the stars. But these were pale imitations of the mote from the MotherFather, and they were there for the animals and plants to survive.
The MotherFather even gave one to the Other. But from what I heard, the Other was a greedy, terrible being. I heard that they wanted everything that the MotherFather made all for themselves. Which meant the Other not only wanted to hoard the motes, no one else could have any.
When the first kin had their sun stolen, word quickly spread. Soon, the others tried to run away from the Other, but there was no escaping for long. The only way they were able to safeguard their personal sun was to hide it away inside themselves. Which was when the first kin began to glow from the sun peeking through their skin as markings or shining from behind their eyes.
Of course, a good number of kin felt sorry for their brethren who were bereft of the MotherFather's essence. So be it out of the spirit of generosity or perhaps even love, some kin shared their sun. In distributing their mote, the amount swallowed was not enough to illuminate them. But they were still just as warm, just as full of life as if they had swallowed their own sun.
To this day, each kin is born with their own sun. Though not everyone gets the same size of sun. And that's why some kin have glowing marks and others don't.