What are the Nephilim?
While examining Genesis 6:1-4 and the word נְפִילִים from verse 4 many scholars have come up with a variety of conclusions.
"Now it came to pass, when men began to multiply on the face of the earth, and daughters were born to them, that the sons of God saw the daughters of men, that they were beautiful; and they took wives for themselves of all whom they chose.
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" Genesis 1-4 NKJV
Some say the word is translated literally Giants as it has been in so many English translations.
Others see them as the demonic unholy offspring of Angels (sons of God) and humans, citing Verses 1 and 4.
Borrowing from this theory, many UFO researchers and Ancient Alien theorists see the sons of God as aliens who bred with humans and produced the Nephilim: human/alien hybrids.
So which one is true? Throughout history many scholars espoused one of these theories or another (primarily the first two; the Ancient Alien theory is a modern viewpoint not within traditional biblical scholarship) and this interesting article addresses this issue in a thorough and scholarly manner. Follow the link below.