Epic of Gilgamesh: (Union of Heaven and Earth) called Annunaki
Bible (Sons of God and Women of Men) called Nephilim
The Nephilim were the offspring of the "sons of God" and the "daughters of men" according to Genesis 6:4; and giants who inhabited Canaan according to Numbers 13:33. They were described as "giants."
The Sumerians text, Epic of Gilgamesh, the Annunaki were supposedly the offspring of two deities; Anu and Ki. This is also associated with supposedly alien deities. They were often described as very tall and even shapeshifting.
Interestingly, the Bible and The Epic of Gilgamesh both told of a flood to obliterate mankind and both describe these half God/half human type offspring who were reported as tall. When you see several cultures trying to explain something unnatural, you have to wonder if there was something on earth that needed explaining.
Dr. Melba Ketchum's recently reported Bigfoot DNA report told of a novel hominin that mated with a modern human and created an offspring known to us today as Sasquatch or Bigfoot. Reports were that this novel hominin suddenly showed up in Bigfoot gene pool, but not our gene pool. The conclusion of this would have to be one of three possibilities; this novel hominin is one we have not dug up yet and archived DNA for, it was of alien (outside) origins, or it was the Nephilim/Annunaki.
Let's make a case for each of these scenarios -
Most likely logical explanation (Okkam's Razor) is that there was a hominin that we have not accounted for yet. The problem with this is that this novel hominin DNA has not shown up in the general population that we know of. So, if it was mating with humans in the past, the only thing it mated with was a few women who made these future Bigfoot offspring. If we can find traces of Neanderthal or Denisovan in our gene pool throughout continents, this fellow should be swimming around in our genes too.
In the scenario that involves an alien outsider, the hardest part to imagine here is that this alien being was able to mate with human women and create offspring. The options here are that this alien was already part of our genetic origins, a relative of our ancestors (hard to believe given his physical difference - if he added the height and hair-covered body to the Bigfoot attributes) or DNA manipulation was undertaken (think in terms of alien abductions and impregnation). Why they would wish to do this and then leave these tall hairy beings to hide in the woodlands doesn't make any sense. Bigfoot doesn't appear to have any important mission here or reason to "invent" him.
The last scenario involving Nephilim/Annunaki, is very ethereal, based on folklore and grandiose stories of angels and aliens. As ridiculous as these concepts seem, two separate ancient texts speak of similar happenings which seems to support some seed of truth. What happened in our past to conceive of such notions? Did they encounter these unusual beings and come up with an explanation for it and, given their knowledge of natural science was lacking, they attributed it to something magical in origin? If aliens or angels mated with humans, why? And why would they even have DNA to add to a physical being? Why the drive to mate? And, wouldn't these half-breed superhumans be dominating upon the earth and not quiet shy creatures?
The times we are most likely to contemplate the Nephilim/Annunaki in reports of Bigfoot being other dimensional or having oddly persuasive psychic abilities, disappearing in mid step, and mentally speaking to us. These sorts of otherworldly attributes would lead one to this explanation for Bigfoot's origins. Why does he stay shy and hide from us? Why is he able to evade us so well? The answers could be in an angelic or alien origin. At least, this is what believers interpret.
And, back to Dr. Ketchum's study; if this truly is revealing something novel that showed up out of nowhere and mated with some women, starting this race of giants, one would have to reconsider the notion of Nephilm - the sons of God and daughters of man - a union on earth that could have had lasting effects for a population called Bigfoot.