No thank you, Chuck Missler is out there, if you go back to when the History Channel started their "Ancient Alien" series Chuck was a big contributor. The American Hero Channel, has the opposing view and they call it the "Cult of the Aliens"
Chuck believes that aliens are going to come to the earth before Jesus comes back. His teachings on fallen angels as the sons of God is "reading what you believe, not believing what you read" the context of Genesis 4:14-6:2 does not introduce any one other then Cain's generations and Adam/Abel's generations. Take Genesis 4:14 to 6:2 copy/paste all the verses in word or pages, take away the verse numbers, keep the chapter brakes and you cannot come to the conculsion that the sons of God are fallen angels. Stay in the context, you do not need to go to any other place in the Bible or anything outside the Bible, just stay in the context.
A simple reading of Genesis 6:4 shows that the Nephilim were already on the earth in the days that the sons of God came in to the daughters of men and after they came in to the daugters of men as well. Verse 4 also says that the children of that union of the sons of Gos and the daughters of men, they were mighty men of old, men of renown. Read it, there is no special way to understand this verse is is what it is. You need to "believe what you read, not read waht you believe"
“The Nephilim were on the earth in those days, and also afterward, when the sons of God came in to the daughters of man and they bore children to them. These were the mighty men who were of old, the men of renown.”