Mutation: A rare and random chance for a variation in genes.
A Mutation could be caused by A significant environmental factor or a specific set of events occurring during cell division. In a particular baby in the Saiyan incubation room, the hormone responsible for the creation of the cell which slowly diffuses S Cells into the body died prematurely, the brain noticed this and commanded the body to produce more however due to a malfunction in the electrical impulse sent by the brain to the effector, more cells which secreted S cells were created than necessary. This resulted in the number of unsecreted S cells in the body to go from around one thousand to one million. This was an invisible occurrence that went entirely unnoticed by the strange caregiver aliens that were responsible for the maintenance of Saiyans still inside incubation pods.
After conquering many planets in the name of King Cold as well as the Royal Academy of Science, the study of Science dramatically increased. In the entire universe, the newly christened Frieza Empire was probably the only one which accidentally spread mass knowledge throughout multiple systems. In the eyes of the Frost Demons, it made sense to increase the scientific capacity of their empire which consequently industrialised planets that were formerly hermits unaware of basic science. Races with unused potential in memorisation and understanding of Science caused consecutive breakthroughs.
This influence consequently reached the Saiyans meaning that some of the top scientists, including Dr Challenger - a scientist currently collaborating with the Saiyans under the command of Frieza, caused some biological breakthroughs as well. After multiple experiments, Dr Challenger managed to isolate and reproduce the S Cells artificially then combining it with the incubation liquid used for Saiyans in the incubator and the S cells in the liquid diffused into the Saiyans' body, this meant every generation of Saiyans had more potential than the last due to inheritance. For some unknown reason, the S cells only functioned in Saiyan bodies, when transferred into other organisms the effect was almost negligible.
Three years later the mutated Saiyan was brought out of the incubation chamber by a funny-looking purple alien and a tall muscular man that stood behind him.
"What are you waiting for? Hurry up and check his Power Level!" The tall man shouted at the purple looking alien, startling the alien.
"Ok! OK! You're seeing your baby for the first time and all you care about is power levels? You Saiyans are worse parents than I thought," the purple alien said in a judgemental tone.
The tall man, named Paragus, turned a deaf ear to the alien, Saiyans were a fighting race - meaning that your standing was based on your Power Level so all parents naturally wanted the best for their children, however, this didn't translate well to other races.
The purple alien squinted.
"What's the matter?" Paragus said in a worried voice, his irritation barely evident.
"His power level is .... high, so high it must be a mistake, on top of that the numbers keep changing, Yes there is clearly something wrong with scouter." The purple alien said justified in believing there was no way a baby could be on par with the current monkey king.
Paragus did not know how to feel, on the one hand, his baby was strong but on the other hand, it could be due to a scouter malfunction.
"But these Scouters were supplied by Freiza himself there is no way it could malfunction, Right?" Paragus reasoned with the funny looking alien.
The alien paused seeming to be lost in thought.
Paragus grew impatient and snatched a scouter from a nearby worker, equipped it and said: "What is your power level?"
The alien blushed, embarrassed and said "13"
A clear and visible '13' appeared on the Scouter Paragus wore, Paragus then turned to look at his son.
Paragus gasped, his eyes widening and almost cried tears of joy.
"T-T-TEN THOUSAND?????" he shouted drawing the attention of the workers and scientists in the incubation room.
Paragus picked up the baby swinging it around and hugging from time to time, while rejoicing saying his hard efforts were finally recognised. A grown muscular man showering his child with affection.
The workers and scientists in the room stared at Paragus dumbfoundedly, they had never seen a Saiyan express emotion other than being hungry or angry. In all reality, Paragus was a gentler Sayain in the first place so he found contentedness very easily. The baby was fast asleep completely unaware of the uproar it had caused by being born.
"Uh, Paragus? We need to report this to King Vegeta immediately," One of the upper-class Saiyans said awkwardly, he too had never seen a Saiyan jump for joy in his 30 years of existence. He didn't actually believe that the baby was so powerful, he thought it was a Scouter malfunction and that needed to be recognised. It didn't make sense for a three-year-old to be on par with the current king, it was more likely Freiza would hand over his current empire to the weakest creature he could find, out of the goodness in his heart - nigh impossible.
Saiyan Ranks were decided at birth. In accordance with the power level they had, a low-class warrior had a power level of around 1-70 at birth, a mid-class 71-140 and the elite 141-200 with King Vegeta's son being the highest known case at 280 at birth. If the baby's power level was correct, not only did that mean that as a child, the baby could fight one on one with King Vegeta and it would be close but also that every other Saiyan in comparison looked like complete garbage-water trash-tier individuals. All the Saiyans that heard the news were more likely to believe God himself came down and possessed the baby no wonder Paragus was so excited such a monster came from his loins.
Paragus and several warriors arrived at King Vegeta's palace where a meeting was taking place.
"And then I asked her, do you want it all at once or just the tip?" King Vegeta said with a cocky expression.
Laughter broke out amongst all the ministers in King Vegeta's palace.
Suddenly, a guard burst through the door, "King Vegeta! There are reports of a Saiyan baby with a Power Level over ten thousand!"
PFFFFFTTTTTTT!!!!
Freiza who was eavesdropping on the conversation through the Scouters suddenly spat out his juice.
"What the fuck did I just hear?" Freiza shouted aloud.