CathInfo.com

 But what the Ancient Aliens folks characterize as "aliens" were actually these Nephilim angels.

Didn't change the caption previously:

Enochs biggest weakness is often overlooked. Giants are both before AND after the flood. If the angels had half breed children and those children were wiped out, how is it that the same term is used when Israel goes into the promised land? After all Noah was perfect in his 'generation' (either meaning, spiritual (my understanding) or physical).

Genesis says that Noah (and by extension, his sons) were "perfect in their generation".  Right before this verse, it says Noah was "just".  So "just" would mean Noah was spiritually good, while "generation" would refer to his physical nature/genes.

The easy solution to how the Giants existed post-Flood is due to sin.  Noah's son's WIVES were not perfect, so ergo, Noah's grandchildren were not genetically pure.  Thus, when Noah cursed Canaan, then this line of people became both physically/spiritually cursed.  And they devolved (again) into witchcraft/satanism, just like it existed pre-Flood.  The stories of the Israelites seeing the Giants always related to one of these offshoots of Canaan (i.e. all those peoples who had Giants were not followers of Israel.  They were enemies of God).  This culminated in Nimrod and the Tower of Babel.  How do you think the great Tower of Babel was built?  Giants, of course.  They probably also built all the other ancient wonders (pyramids, easter island figures, etc).

These peoples worshipped satan and this is why God always told the Israelites, after conquering these tribes, to kill all living things (humans, animals, food) and burn it all.  Because these things were cursed and deformed (physically) and an abomination (spiritually).

I personally don't believe that Nephilim meant half breed angel children as I don't even think angels have physical bodies (and no marriage in heaven).

Many, many Church Fathers support the idea.  St Augustine and Anne Catherine Emmerich delve into the science of it and basically agree that the fallen angels used witchcraft to manipulate genetics (of people who opened themselves up to the demonic) and create super-human beings.  Maybe these fallen angels even inhabited these bodies?  I don't know.  Scientifically, genetic manipulation is possible.  Back then, it was probably more possible than today.

Many, many Church Fathers support the idea.  St Augustine and Anne Catherine Emmerich delve into the science of it and basically agree that the fallen angels used witchcraft to manipulate genetics (of people who opened themselves up to the demonic) and create super-human beings.  Maybe these fallen angels even inhabited these bodies?  I don't know.  Scientifically, genetic manipulation is possible.  Back then, it was probably more possible than today.

I actually believe in the notion that there were a lower class of angel that were composite beings, not pure spirit, so similar to what disembodied human souls are now (before the Resurrection) except that having bodies for them was not of their essence ... though they could assume bodies.

We need merely look at Genesis 18 where 3 angels appeared to Abraham as men, and ate the meal Abraham prepared for them.  So if these angels could eat meals, they could also certainly interact with human women.

Now, both Genesis and Enoch say that these angels were enticed by the beauty of women, which could not be the case if they were PURE spirits.  But if they were partly-sensible, per my hypothesis, then it certainly could make sense.