"There were
N E P H I L L I M
in the earth in those days; and also
after
that, when the
                                        sons of God  the daughters of men, and they
bare children
to them, the same became
mighty men which were of old, men of renown".
(Gen.6:4)

       I want to make this perfectly clear, the word "giants" translated in your bible is a clear cut INTERPRETATION LIBERTY from the Greek. The wrong "root" was chosen for the translation of the word "giants" on purpose. 


The root that was used is gigantes (giants), but thats NOT correct. Yes, they were "giant", but that is not WHAT they were. 


The translators did not interpret from the source root. The primitive root of "gigantes" in the Greek translates "gigas", meaning EARTHBORN. 


They are also called "gibbhor" or "gibborim" in the Hebrew. 


The King James bible is translated from the Greek and Hebrew from cover to cover. In the case of Gen.6:4, the translators specifically chose the Septuagint LXX for the word "giants", which was translated from Hebrew to Greek. 


The reason being the source origin Hebrew translation is too "un-believable" ( though true), because the translators REFUTED the "angel view".


The correct translation in the Hebrew is


[Strong's ref. 5303 nephiyl - nef-eel; prop. a feller, i.e. a bully or tyrant: - giant]. 


Its proper use in the plural for this word is NEPHILLIM (giants). 


Though this is the root given, it is NOT all of the meaning of the word. 


You must "trace the roots , to find the fruit".  


[Strong's ref. 5307 naphal- naw-fal; a prim. root; to fall, be cast down, cease, fugitive, die, fail, be judged, throw down]  


Also the ancient chaldean root [Strong's ref. 5309 nephel- neh-fel; something fallen, i.e.an abortion].


Though these are descriptive words for these "offspring" (nephillim), they are much more descriptive of their "fathers" who bore them. 


What seems to give the credence to the "rape" scenario, is the use of the words "...came in unto..." in Gen.6:4. It implies that of "forcefulness". Also, the term is "...and they bare children unto them". It might not seem curious to you at first, but God already stated at the top of the verse that"... there were nephillim (giants) in the earth in those days...". 


He is emphasizing the fact that there was a definite "sexual union" between human females and "fallen angels", creating aHYBRID progeny called the nephillim. 


These are what are referred to in ancient mythology as DEMI-GODS(half man - half God).


TITAN = Greek
SHEITAN = Chaldean
SATAN = Hebrew