Hello Narkissos! (and I have to go (for now) after this post),
1 Enoch 39:1f most probably refers (again) to the union of the heavenly Watchers with women... so "?"
Good question; I've asked that and much more about the text in question. This led me to an 'in-depth study' (to the best of my ability) of Genesis 6:4 and of the Nephilim.
To abbreviate my findings; I see 1 Enoch and Ge. 6 (Nephilim) as a kind of apocalyptic description of (what we normally refer to as) "The Fall of Man." However, this wouldn't be the "original Fall" (of Adam & Eve).
It's the later Ante-Deluvian (before the flood) Fall, imo, described in apocalyptic phraseology or terms. Put another way, the "race" of the fallen ones (lit., nephilim) began at this time.
Though there were a certian people specifically identified as "Nephilim" I do not see them as some kind of mysterious "giants" (which is due to an erroneous translation in the LXX). Nor do I see them as a strange "Bible Science-Fiction-Giants" (or the as the object of jokes).
Essentially, being "born of (or by) a spirit" or having a spiritual-birth and, therefore, being "in" a spiritual-family is what I'm driving at. I believe the Bible (and extra-canonical literature as well) points to "people being in One of the Two Families" by virue of their spiritual birthright.
1 Enoch 15 (Charles translation)
1. And He answered and said to me, and I heard His voice: 'Fear not, Enoch, thou righteous man and scribe of righteousness: approach hither and hear my voice.
2. And go, say to the Watchers of heaven, who have sent thee to intercede for them: "You should intercede" for men, and not men for you:
3. Wherefore have ye left the high, holy, and eternal heaven, and lain with women, and defiled yourselves with the daughters of men and taken to yourselves wives, and done like the children of earth, and begotten giants (as your) sons?
4. And though ye were holy, spiritual, living the eternal life, you have defiled yourselves with the blood of women, and have begotten (children) with the blood of flesh, and, as the children of men, have lusted after flesh and blood as those also do who die and perish.
5. Therefore have I given them wives also that they might impregnate them, and beget children by them, that thus nothing might be wanting to them on earth. 6. But you were formerly spiritual, living the eternal life, and immortal for all generations of the world.
7. And therefore I have not appointed wives for you; for as for the spiritual ones of the heaven, in heaven is their dwelling.
8. And now, the giants, who are produced from the spirits and flesh, shall be called evil spirits upon the earth, and on the earth shall be their dwelling.
9. Evil spirits have proceeded from their bodies; because they are born from men, and from the holy Watchers is their beginning and primal origin; they shall be evil spirits on earth, and evil spirits shall they be called.
10. As for the spirits of heaven, in heaven shall be their dwelling, but as for the spirits of the earth which were born upon the earth, on the earth shall be their dwelling.
11. And the spirits of the giants afflict, oppress, destroy, attack, do battle, and work destruction on the earth, and cause trouble: they take no food, but nevertheless hunger and thirst, and cause offences. And these spirits shall rise up against the children of men and against the women, because they have proceeded from THEM.
divisions, emphases, & caps, mine
\o/
I have to go for now....