There exists an extradimensional race that call themselves the "Beings of Light." They are capable of such immense powers, that the most powerful among them, their leader, is viewed by many of them as a god. However, it does not like to be referred to as such.
Approximately 160,000 years ago, the Beings of Light discovered and recognized the potential of humanity. A group of Beings of Light transplanted a large number of humans to another planet tens of thousands of light-years away and 'civilized' them. Upon gaining a new language, the humans named their new home planet "Kobol" and began calling the Beings of Light, the "Lords of Kobol." They developed an entire religion around these Lords of Kobol. Eventually, the people of Kobol also developed a civilization with all the amenities of an advanced society (e.g. automobiles, television, advanced medicine, etc.). They even created artificial life forms such as sentient machines. Known as "Cylons", these artificial life forms served as a slave caste. At some point, they rose up and waged war against their masters.
Eventually, the war so devastated Kobol that both humans and Cylons fled the planet. Using a space-folding technology that enables space ships to make instantaneous "jumps" across vast distances in space, the humans went on to colonize twelve separate worlds in a single star system, becoming the "Twelve Colonies of Kobol". Simultaneously the Cylons colonized a planet they named "Earth" (the first planet to bear that name). On this Earth, a race of biologically-reproductive organic humanoid Cylons became the dominant species and they enslaved mechanical Cylons.
Eventually, history repeated itself and the mechanical Cylons rose up and waged war against the organic cybernetic life forms that were their masters. During this war, the Beings of Light observed the conflict. Some of them appeared to five humanoid Cylon researchers in the form of visions and warned them of the impending destruction of their planet's population. After a nuclear conflagration that did indeed destroy the planet's population, the only survivors were the five researchers. They survived by re-inventing a technology from Kobol called "organic memory transfer." This technology "resurrects" a Cylon upon their body's destruction by saving their consciousness and then "downloading" it into an identical clone body.
These "Final Five" surviving humanoid Cylons realized that the humans of the Twelve Colonies would continue to create artificial life. So they headed for the Colonies to tell the humans to treat their creations well and keep them close. Because their people hadn't developed "jump drive," the Five's ship traveled at relativistic, but subluminal speed. Time slowed down for them, but thousands of years would pass before they finally reached the Colonies. Along the way, they stopped at the Temple of Hopes, a temple that was created by their ancestors where they prayed and got a sign that led them to their "Earth."
The humans on the Twelve Colonies initially lost most elements of civilization from Kobol after they settled on the twelve worlds. However, the Beings of Lights had given their ancestors a capacity for genetic memory. This genetic memory does not take the form of passing on personal memories, but of an unconscious knowledge of certain invented concepts and ideas such as technology, language, engineering and even fashion and music along with various other aesthetic cultural aspects.
Over a period of a couple thousand years, all the technological and cultural aspects form Kobol completely reconstituted because the genetic memory of these concepts and ideas 'leaked' into the subconscious minds of various people who gradually and collectively reinvented these aspects of Kobol society. Eventually, even the genetic memory of the concept of artificial life in the form of Cylons was reconstituted in the conscious minds of such men as Daniel Graystone and Tomas Vergis.
Eventually these new Cylons were used as slave labor within the Twelve Colonies. As had happened before, they eventually rose up and waged war against their masters. By the time the Final Five humanoid Cylons arrived at the Colonies, the humans had been fighting the Cylon Centurions for over twelve years. The Centurions were already trying to make flesh bodies. They had created the "Hybrid," but nothing that lived on its own. Remaining a secret to the people of the Twelve Colonies, the Five offered the Centurion Cylons a deal: if the Centurions agreed to end the war with humanity, the Five would create organic humanoid Cylons for them. The reason the Five were so willing to create new humanoid Cylons was that the Centurions had developed a belief in a single loving God. One of the Five, Ellen Tigh, believed it changed everything; if the Cylons embraced love and mercy, then the cycle of violence could end. The Centurions agreed to the deal. With the reason being kept secret from the Colonials, the Cylons agreed to an armistice with them and left the system.
The Five and the Centurions then withdrew to a planetoid-sized mobile space station called "The Colony" placed beyond the Armistice Line. The Five then developed eight humanoid model Cylons, which were designed upon their own physiology. They created "Number One" first and named him John, after the father of Ellen Tigh. He was also made in the image of Ellen's father. John helped the Five build the other seven humanoid models. Ellen was close to Number Seven, Daniel, and John, out of jealousy, contaminated the amniotic fluid in which the Daniel copies were maturing and then corrupted the genetic formula. This wiped out the copies permanently.
John rejected mercy. He had a twisted idea of morality, so he turned on the Five. He trapped them in a compartment and then he took the oxygen offline. John boxed the Five at first but ultimately unboxed them and downloaded them into new bodies, but he blocked their true memories and implanted false ones and introduced them one by one into the colonies. He introduced Saul Tigh first, not long after the Cylon War ended. Several years later, he introduced Ellen Tigh. Over the years, he gradually introduced Galen Tyrol, Samuel Anders, and finally Tory Foster. Cavil put the Five into the human population in order to truly show them what humans are like. He hoped that when they died and resurrected (which would restore their real memories) they'd be ready to admit they were wrong.
John erased all knowledge of the Five's identities from the minds of the other surviving active humanoid Cylon models. Although the other six knew about the existence of the "Final Five", they did not know their story, what they looked like, and were even programmed to never speak of the Five or search for their identities. Only the Number One models knew the truth of the Final Five; a fact unknown to the other six models.
Adopting the name "Cavil", the Number Ones still wanted justice for the enslavement of the Centurion Cylons and convinced the other Cylon models to the same thinking. During their forty years of isolation, the seven active humanoid Cylon models never stopped hating humanity. For them, the war never ended. It had simply evolved as they had evolved.
During this time, the humanoid Cylons created more "Hybrids" to pilot their basestars. The Beings of Light would communicate with these Hybrids. They even communicated with the First Hybrid as well. Realizing the impending destruction of the population of the Twelve Colonies, the Beings of Light also chose a young girl named Kara Thrace to serve a special purpose. She would one day bring the survivors of the Twelve Colonies to the home world of the human species, our Earth.
After the attack on and destruction of the population of the Twelve Colonies of Kobol, a Being of Light appeared to Dr. Gaius Baltar. Appearing in the form of a Number Six model humanoid Cylon, she would appear to him on a daily basis for the next several years and influence him towards events that inevitably would lead the remnant human Colonial population towards our Earth.
Over the next few years, the Beings of Light would give several people visions and appear in different forms to several others, such as a Number Six model humanoid Cylon named "Caprica." The Being of Light that would appear to her appeared in the form of Dr. Baltar. The Beings of Light would also give a Number Three model humanoid Cylon partial visions of the Final Five in between resurrections. Eventually, they gave her a full vision of the Five while she was at the Temple of Hopes (by then it was known as the "Temple of Five").
Sometime after this, a Being of Light appeared to Kara Thrace in the form of the Number Two model humanoid Cylon known as "Leoben Conoy" and then the Beings of Light transported Thrace and her Viper to the Cylon-colonized "Earth" in a process that visually looked as if Thrace and her Viper had been destroyed. Upon arriving on that Earth, Thrace's Viper crashed landed, killing her. However, the Beings of Light immediately saved her consciousness and then downloaded it into a perfectly replicated body. They then placed the resurrected Kara Thrace in a newly-built replica of her Viper and sent her back to the battlestar Galactica and the remnant human Colonial fleet with slightly altered memories of her voyage to the Cylon-colonized Earth. They also placed the "jump" coordinates to our Earth within her subconscious and the jump coordinates to the Cylon-colonized Earth within the navigational computer of the replicated Viper. Several minutes before she was returned to the Fleet, the Beings of Light used a musical tune to make the four members of the Final Five who were within the Fleet aware of their nature as humanoid Cylons. The Beings of Light would also later, use this musical tune as a way to bestow upon the human-Cylon hybrid Hera Agathon the jump coordinates to our Earth.
Eventually, the Beings of Light subconsciously made the four of the Final Five within the fleet aware of the jump coordinates within the replicated Viper and it was used by the Fleet and a rebel Cylon basestar to lead them to the Cylon-colonized Earth. Arriving on the planet, they discovered the ruins of the destroyed Cylon civilization. Several months later, the circumstances of a battle led Kara Thrace to finally bring the Galactica to our Earth. Upon discovering human beings on this Earth, the people of the Fleet gave the planet the name "Earth" and decided to settle and cast aside their technology to join with the pre-verbal tribal human population. The surviving humanoid Cylons joined them on Earth. Soon after the settlement began, the Beings of Light transformed Kara Thrace into one of them. She joined the Beings of Light on a higher plane of existence.
The survivors of the Twelve Colonies went on to interbreed with the native Earth-evolved human population. Hera Agathon would have so many descendants that they would go on to breed with people all across the entire world and eventually every person on Earth would be a direct matrilineal descendant of Hera Agathon, meaning the entirety of humanity became partially of humanoid Cylon heritage.
As the human Colonials interbred with the unmodified original Earth humans, the genetic memory capacity was diluted and became latent. It took more than 140,000 years before it became active again. After the end of the Stone Age, the capacity began to reemerge and certain ideas and concepts reemerged. However, they reappeared only in rudimentary, fragmented and even modified forms. For example, the Colonial religion gradually reconstituted in the minds of the people of ancient Greece - but in a modified form (e.g. the "Lords of Kobol" became the "Gods of Olympus).
Over a period of several millennia, a multitude of Colonial ideas, concepts, and cultural aspects reemerged because of genetic memory. Although they would continue to reemerge in rudimentary, modified and fragmented forms, eventually these fragments coalesced into complete reconstitution of Colonial aspects. For example, the Colonial language eventually reconstituted as the "English" language. The English language did not suddenly appear, but instead evolved through centuries of modifications along with amalgamations from numerous other languages. It was all the result of the genetic memory of the language 'leaking' into the subconscious minds of people who unconsciously directed the language toward a linguistic endpoint that is an exact replication of the Colonial language (apart from a certain profanity word).
As a result of genetic memory, by the early 21st century virtually every cultural aspect of Colonial society has reemerged: language, names, fashion, engineering, architecture, furniture, music, art, cuisine, household appliances, television, automobiles, federalized government, judicial systems, labor unions, military protocols, etc. Countries such as the United States, Canada, and the United Kingdom collectively form a near perfect replication of the society of the Twelve Colonies of Kobol more than 150,000 years ago – just without advanced technology such as jump drive and sentient machines...yet.