And the LORD said, "My Spirit shall not strive with man forever, for he is indeed flesh; yet his days shall be one hundred and twenty years." There were giants on the earth in those days, and also afterward, when the sons of God came in to the daughters of men and they bore children to them. Those were the mighty men who were of old, men of renown.

Then the LORD saw that the wickedness of man was great in the earth, and that every intent of the thoughts of his heart was only evil continually. And the LORD was sorry that He had made man on the earth, and He was grieved in His heart. So the LORD said, "I will destroy man whom I have created from the face of the earth, both man and beast, creeping thing and birds of the air, for I am sorry that I have made them." But Noah found grace in the eyes of the LORD." Genesis 6:1-8
The population of Planet Earth before the Flood was around 9 billion people. God created "Spaceship Earth" to comfortably house in excess of 9 billion people. Notice the Bible uses the term the "sons of God." The implication here is that these were not mere natural men, they were the offspring of fallen angels mating with "the daughters of men," or human women. Thus fallen angels had sexual relations with human women producing an alien-human hybrid race called the Nephilim. These Nephilim were the "giants of old" and had DNA that was a combination of demonic and human DNA. This violated one of God's deepest laws and was the ultimate reason why God destroyed the human race with a Flood.
In our time a movement called transhumanism is attempting to create a post human race in secret laboratories where animal and human DNA are being combined, along with the possibility of Nephilim DNA. Governments around the world are attempting to create Cyborgs or genetically enhanced warriors. When we read the Book of Revelation there are horrifying creatures that are not symbolic, I believe these creatures are the products of demonic and human interbreeding in order to create Cyborgs.
I go into how the coming one world government, one world economic system and one world religion will incorporate transhumanism and genetically altered beings that are monster-like. The biotech industry will create a new "space race" and generate trillion of dollars industry.