Okay, so I might have spelled it wrong ( just throwing it out there ). A Nephilim ( from my research ), is half-angel and half-human. This dates a little bit into the biblical area ( Catholicism)- ( again going off of what I read ), okay back to it, or should I say to start this. Okay, most people would agree to disagree that their real, but for the time being, let's assume their actually real ( Nephilim's ). Just to make people think out side the book, kinda a brain tester sort of thing. Anyway, say Nephilim's are real, how would one truly know they are one ?? Again this is to test the limits of the mind and think on a different frame of mind, so I know their not real, so.
If you believe the Book of Enoch, the tale of the origin of the Nephilim (which are only mentioned twice in the current Bible), then it would be obvious: They were giants. Having a height of ten feet or more, and not in the lanky sense of people with certain genetic disorders; giant with the structure and cardiovascular ability to become warriors.
There is but one version of them. Their supposed origin is in the book of Enoch. They are mentioned but twice in current canonized scriptures. Their existence is purely mythological. They are not real, nor were they ever.