I just do not see it. There is nothing in Scripture that MUST be taken as speaking of angel/human breeding.
And then, last but not least, there is also that unattractive story about Cain actually being the son of Satan.
I cant seem to find that one anywhere.
Gen 6:1And it came to pass, when men began to multiply on the face of the earth, and daughters were born unto them,
That the sons of God saw the daughters of men that they [were] fair; and they took them wives of all which they chose.
There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare [children] to them, the same [became] mighty men which [were] of old, men of renown.
You may disagree with the above, but when it comes to the Bible, there are as many different opinions as there are students of it (the Bible).
That said, exploring the Bible is like brushing away sand at an archeological dig...it may be a slow process but it occasionally reveals an amazing view into our distant past.
Gotta run some errands but thx for taking time to chat about this stuff.