Prompt: A segment of the population does not believe anyone ever walked on the moon. Some probably do not believe their species ever gained space travel. What happened to them when so many members of the population left for the stars? -- Anon Guest
Space was hard to ignore for a conspiracy theorist. It was impossible for humans to leave the Earth. Simply impossible. The fact that so many of their fellow humans were doing it was not a fact at all.
Galactic humans, centuries after their colonial forefathers slipped the surly bonds of Earth, called it The Shattering. With ominous capitals. But what it was was pieces of Terran culture hurtling down time and space to other worlds. Some of it has yet to be seen again.
And those left behind did not feel it was their duty to maintain a backup. Most found the contents of Earth's vast and scientific libraries to be heretical, when they weren't found to be blatant untruths. Only the most convenient of the sciences were allowed to persist. Those who maintained them and knew some of the truth were permitted to continue, but science as we know it went underground.
Those remaining behind could implement their isolationist ideas without fear of opposition.
They called this a good thing.
Earth became a miserable place to live. It was no surprise that those who saw the winds of change fled for either nearby planets or the stars. Populations plummeted.
Those left behind, fervent in their fanaticism, saw this as a sign from their god. There was little time for luxury, since it took ten people with their feet in the mud to keep one with their head in the clouds. Therefore, the remainders shunned it. They turned away from technology and business, and went all the way back to making their own bread by the sweat of their brow.
They called this a good thing.
Those who did not fit the rigid rules of their society, those who asked too many questions, and those who thought too long on subjects they should have ignored... those were exiled. Left to find their way in the wilderness.
They continued on, in willful ignorance, and let the rest of the world, the rest of the universe, pass them by.
And they called this a good thing.
It was the exiles who found each other. Who read or recited the surviving teachings. Who looked at the way things were taught and who looked at the way things were and said, "These don't match." They did not know what was true, but they were determined to find out.
It was the exiles who banded together and founded new cities. Who found new ways to breed wheat or crops. Who revived science from its ashes and uncovered truth after truth. Who found, after centuries of oppression, ways to grow food that didn't require vast tracts of land to support those who lived there.
And it was the exiles who went underground, much like Jules Verne's Morlocks, and found remnants of a world that once was. A better place. They hunkered away from the militant and violent isolationists. Kept themselves safe from those who would kill anyone who soiled their world view with truth. Found ways to communicate with the colonies on the Moon or on Mars.
We are here, they said. We seek the truth.
The isolationists saw aliens visiting far-flung mountains and distant, forbidden soil. They weren't very wrong, not really. Those who lived on Mars and those who lived on Luna were changed by their time on other planets. Some were taller and frailer. They had to wear special bracers to protect themselves against the heavy gravity of Earth.
They brought with them the forbidden knowledge. Things they thought worthy and worth keeping. They brought vital DNA samples, of stronger genetics that they had been working on whilst the isolationists kept inbreeding themselves to the brink of destruction.
And they brought a mission to save humanity.
In secret, in the cover of darkness and with special sedatives, they invaded the isolationist colonies and implanted embryos with improved DNA. Some were inserted into married women. Some weren't. If the isolationists saw something in the rise of 'virgin' births and 'miraculous' pregnancies, they did not tell anyone but each other.
Many had lost the art of literacy. They could not write their stories down, only pass them on to their own.
It took well over a century, but the suspicions of the UFOlogists came true. Beings from other planets did come down from the sky to implant their children in unsuspecting human women.
They would likely never know, but this was a good thing.