(Author's note: This is a rework of my first story in a different setting and without some story elements that I was not happy with, including the main male character's "size" and the setting itself.)
FROM EARTH TO THE STARS
Tyler and Jessica were one of the many couples that had boarded the massive spaceship that had left earth a year before. Headed to a chartered new world decades away, the ship was made up of countless independent compartments that acted as fully self sufficient units. There was no shared space, each unit was furnished with technology that provided everything they needed. As it is not the focus of the story, we will not get into the specifics. But units each had a double bunk bed, a device that provided food and drinks, a shower and toilet and a small area for living. Units had no windows but had virtual screens providing artificial daylight and space vistas.
Both 25 with engineering backgrounds, they had been chosen for their part in designing some of the ship's systems. Each couple was allowed to have two kids, after which a pill given to the males made conception impossible.
While Tyler was fairly average in looks and physical build, he had charming eyes and was skilled at seduction, which is how he started dating Jessica Diaz in the first place. She was way out of his league. Inches taller, Jess had striking green eyes and short dark hair but it was her body that stood out. Naturally curvy with a narrow waist and breasts too large for her size, she was quite the beauty. And her high ass was absolutely perfect in the tight jumpsuits worn by the ship's inhabitants, shaped like a heart and swaying when she walked.
When Jess became pregnant with twins (technology could detect it early), they decided to have a talk. And as it turns out, both were not moral people at all and were quite a bit twisted when it came to sex and their previous history. The rules, laws and morals of earth did not matter, as their kids would only know what they would teach them, at least until they left the ship. Ultimately, they decided to wait until the twins would be 18, then teach them everything and have fun doing it too.
THE TWINS
Turns out the twins did not look so much like their parents, at least for their body types. While they shared a slightly darker skin, they were very small physically and did not look like each other much. Sarah's hair was kept short for convenience, like the other three.
As she turned 18, Sarah's chest and ass were also much smaller than her mom's due to the difference in physical size, her breasts a bit more than a perfect handful, which caused them to look higher than her mother's. Her dark hair was kept short for convenience, like the other three. Her eyes were startingly blue and bright, larger than average, with full lips she inherited from her mom.
Tyler was only slightly bigger than his sister. His hair was dark and a bit curly and his face was more attractive than his father's. Out of the two kids, he was the most quiet and the one who had adapted the most easily to this life thanks to his vivid imagination and ability to daydream.
At puberty the kids were told what they needed to know and that until they were adults, hugs were the limit but that after that, there were many ways they could all show affection to each other.
To Simon it had sounded rather pure and family-like, but to Sarah it was more.
MIDNIGHT
The parents had not warned the kids of what they were going to do, nor had they said anything about when their 18th birthday was. They had never celebrated birthdays growing up as it didn't feel like it made any sense, so the day would come as a surprise.
For the few hours between bedtime and midnight on the shuttle's internal clock, both Tyler and Jess couldn't sleep as they each wondered what to do and how, with so many possibilities. It was when Simon woke up briefly to shift his position and roll on his back that Tyler noticed it was now 12:01, and that the kids were adults.
Jess noticed about at the same time and turned to look at her sleeping daughter. She gently shook Sarah's shoulder until she woke up, her daughter looking up sleepily at her. "Mom? You okay?"
Nodding with a smile, Jess pulled the blanket from over them and started scooting over to the short ladder of the top bunk bed after flipping the light switch to a quarter intensity and she looked at the temperature control unit to make sure the cabin was warm enough to be comfortable while naked. "Shh, come with me." As her mother crawled on all four for a second before turning around to start climbing down the ladder, Sarah's eyes widened for a second as she saw that her mother was naked from the waist down.
Sarah's heart quickened and she grinned a bit as she realized what was about to happen and what tonight was.
For those handful of seconds that her mom took to start going down the ladder, her curvy butt, tight pink asshole and perfect pussy were in full display and it was the first time that Sarah had seen her mom like that.
Shaking it off, she followed her mom down the ladder and their feet touched the ground at the same moment that Tyler was waking Simon up, the new adult yawning and looking up. "Why are you all up?" He had not noticed his mom's state of undress for now, and he looked at his dad when he spoke.