Here is a theory. I am connecting some biblical dots here but not everyone subscribes to my interpretation I've developed based on those biblical dots.
We know that sometime around 4500 years ago, God saw how corrupt the earth had become, for all the people on earth had corrupted their ways. (Gen 6:5). God said, ... "I am going to put an end to all people, for the earth is filled with violence because of them. I am surely going to destroy both them and the earth." (Gen 6:12-13)
We know that Lucifer fallen to earth, for iniquity was found in him and he was cast from his place in heaven. (Isaiah 14:12-14; Ezekiel 28:12-18). A third of the angels followed him. (Revelation 12:4). Those dastardly guys did not take their ejection well. Satan knew that God had promised a Redeemer from Noah's line, and definitely not wanting a redeemer to be able to emerge on earth, the angels set about polluting the bloodlines of all humans and corrupting them beyond redemption. They were the heroes of old, the mighty men of renown, (Gen 6:4) recorded in every mythology in every culture, and the reason God had to destroy the world and all its people in the Great Flood. (Gen. 6:9)
The Bible describes Noah as being perfect in his generations, indicating that his bloodline hadn’t been contaminated by the fallen angels' and the Nephilim's genetic tinkering, and that his seems to have been the only pure human genealogy left from which a Redeemer could come. (Gen 3:14-25)
We know that genetic tinkering was rampant on the earth even after the high days of the Nephilim when some of the Nephilim tribes still pillaged around the Middle East subsequent to the flood, including the Raphaim, Anakites, Zamzummites, Emites, and, of course, the giant Og, King of Basham. Goliath and his four bothers as described in 1 and 2 Samuel were giants. When 10 of the 12 spies were dispatched to check out the promised land, they were petrified at seeing one of the Nephilim tribes, and even described a grape cluster so large it took two of the giants to carry it. Here we have a glimpse of genetic tinkering with food. Not only were the Nephilim causing destructive mutations among humans and in the food supply, but also in the animals. (1 Samuel 15:3) I personally believe God did not make dinosaurs but rather they were an animal result of Nephilim and fallen angel messing with genes. I also believe the dinosaurs were not invited to the Ark and perished in the flood. I mean, why would God make an animal too big to move with too small of a brain to handle it?
So anyway, genetic messing with our genes was the ploy the fallen angels used to wreck the bloodlines and hopefully prevent the promised redeemer. God called it at the moment when there was only one uncontaminated bloodline left (Noah's was "perfect".) But satan never gave up, we read ahead in history and see how he is active on the earth up to this moment and beyond during Revelation. So would satan abandon a successful tactic of destruction and ruination, corruption and perversion, such as genetic tampering? No. Now when John reminds us that satan comes to steal, kill, and destroy. (John 10:10) Those were the biblical facts. Here is my theory.
Having failed to corrupt man through the direct tactic of genetic manipulation from marriages of themselves to daughters of men, they now pollute the food we eat, embarking on an indirect method to corrupt us. Have you ever wondered why we are experiencing the ever-earlier onset of puberty? It's age 9 now, with onset as early as age 7! Why? Or why we're all huge? Large, lumbering, fat, obese, and taller than ever? We can't even fit on seats anymore from Depression-era movie theaters. Or why autism has quadrupled? Or why suddenly, celiac disease has sprouted up in widespread manner in the population and doctors can't figure out why? ("Increase in celiac disease baffles doctors.") Or why food has to be genetically modified in the first place?
This article wonders the same thing: Is Autism Linked to Genetically Modified Foods?
The genetic mingling happened in the past, is happening now, and will happen again once more in direct manner: In Daniel 2:43 there’s a reference to someone from the fourth prophesied kingdom “mingling themselves with the seed of men” in the last days. KJV: "And whereas thou sawest iron mixed with miry clay, they shall mingle themselves with the seed of men: but they shall not cleave one to another, even as iron is not mixed with clay." Who is the mentioned 'they' mixing with men? Hmmm.
Here is an interesting genetic mutation taking place that's unexpected:
Genetically Modified Crop on the Loose and Evolving in U.S. Midwest
Outside a grocery store in Langdon, N.D., two ecologists spotted a yellow canola plant growing on the margins of a parking lot this summer. They plucked it, ground it up and, using a chemical stick similar to those in home pregnancy kits, identified proteins that were made by artificially introduced genes. The plant was GM—genetically modified. That's not too surprising, given that North Dakota grows tens of thousands of hectares of conventional and genetically modified canola ... What was more surprising was that nearly everywhere the two ecologists and their colleagues stopped during a trip across the state, they found GM canola growing in the wild. "We found transgenic plants growing in the middle of nowhere, far from fields," says ecologist Cindy Sagers of the University of Arkansas (U.A.) in Fayettevillebiotech to it. "One of the ones with multiple traits was [in the middle of] nowhere, and believe me, there's a lot of nowhere in North Dakota—nowhere near a canola field," she adds."
What we eat changes us over time. "You are what you eat." Genetic modification of the creation that God made is doomed to destruction. Satan has been hell-bent on polluting our genes, the world, the animal and the plant world for 6000 years. "The thief cometh not, but for to steal, and to kill, and to destroy: I am come that they might have life, and that they might have it more abundantly." (John 10:10) Fortunately, satan's efforts will have only one last zenith and then he will be bound for 1000 years. He will be loosed for a short time, and then thrown alive into the lake of fire forever. Jesus triumphed on the cross and He is THE VICTOR. All who believe in Him are victors too.