Almost every culture on Earth has some sort of flood myth – and the same haunting feeling accompanies them all, the same nagging suspicion that something so traumatic as to be almost unbearable might actually have happened.
Intense trauma can sometimes hide itself from awareness by short-circuiting the memory; this may be why so many of these stories also seem to imply a sort of collective amnesia, a loss of historical memory which “protects” the human race from ever knowing the terrible truth.
Perhaps the oldest written flood myths are those of the ancient Sumerians; these also serve as the model upon which the Biblical and gnostic flood myths are based.
In the Sumerian version of the flood myth, humanity was created to toil for the benefit of angelic overlords known as the “annunaki,” unruly aliens who both mated with and fought over their creations. Certain annunaki sided with humanity, provoking an uprising; other annunaki responded with the flood in an attempt to reassert control.
In the version of the flood myth recorded in the Jewish scriptures many hundreds of years later, we learn that fallen angels called “the sons of God” came to the earth to mate with human women and produced the Nephilim, cannibalistic giants who ravaged the earth and performed unnatural acts with farm animals.
According to Genesis 6:6, the Nephilim damaged the human genepool so terribly that God decided to exterminate all life on the planet and start over.
The gnostic texts of the early Christian era describe the Biblical creator gods as “archons”, unscrupulous aliens who seeded the planet with life only so that they could exploit it.
According to the myths of the Ophites, the chief archon (identified here with the creator god of the Old Testament) saw that humanity had the potential for divinity, and so decided to drown them:
“[Yaldabaoth] was angry with men because they did not worship or honor him as Father and God; he sent a deluge upon them to destroy all of them at the same time. But Sophia withstood him… and saved those who [had] the moist nature of that light which originated from her; through it the world was again filled with men.” 
Other gnostic myths tell of Eve’s daughter Norea, a virgin who who bore the imprint of divinity. Her mere existence threatened the archons, who resolved to exterminate all life on earth in a flood; as the disaster unfolded, the archons tried to rape Norea and save Noah, but Norea breathed fire, burned Noah’s ark to the ground, and escaped on the wings of angel instead.
But the gnostic myths were not consistent. The Secret Gospel of John, for example, has Noah as the hero who leads gnostic humanity to safety in a “cloud of light”; here the idea was that the “flood” was actually some sort of amnesia-inducing beverage:
“The human beings were made to drink water of forgetfulness by the Chief Ruler so that they would not know from where they had come. For a while the seed of light was cooperative.” 
The Secret Gospel of John also gives a slightly different version of the “Nephilim” story, one in which the fallen angels corrupt humanity after the Flood, not before. Thus most humans were hopelessly entangled in the Rulers’ schemes, forever prevented from remembering their hybrid origins.
THE WTC OF THE ANCIENT WORLD
An epilogue to these events is recorded in the Bible, where the archons descend to the Earth themselves to confuse humans powers of communication and so halt the construction of the Tower of Babel.
One wonders if this could this be why issues of memory and ancestry figure so prominently in all versions of the flood myth – the confusing lineage of the story itself?