Lita Cosner made a good point about human - animal hybrids. If ever there were any hybrid with 75% - 25% or even 50% - 50% of the distinctive genes (as opposed to common ones, hallmark of a common creator) between man and any animal,* it would still be either 100% human or 100% non-human, since man is endowed with the image of God.
This brings up a point about another kind of hybrid. Angelic - human, if that is what the Nephelim were.
I say "if that is what the Nephelim were" since I am reserving in favour of two other possibilities. "Sons of God" being believing Setites and "daughters of men" being impious Cainites is one of them. Angels - fallen ones, not the good ones - acting as cattle breeders (taking semen from one and inseminating in other human without contributing anything except perhaps genetic manipulation) is a view which St Thomas Aquinas seems to have reserved not for the Nephelim in Genesis 6 indeed, but perhaps for what could be considered "neo-nephelim" in legendary men such as Hercules, Romulus, Merlin Emrys (or perhaps rather Martin Ambrose). Being legendary is of course not synonym to not having lived, it is synonym to having evoked sufficient curiosity as to make men tell stories about one.
But assuming either of these views is wrong and Book of Henoch as preserved by Ethiopians gives us the true account, angels do have or are able to assume bodies with real biological functions (St Thomas thinks that whenever angels appear in bodies, these are arranged ad hoc and never really alive, though the angel using them for showing up is). And this includes then the ability to impregnate women. And this was then done by 200 who fell later than other angels through this decision. And their offspring was, in that case, angelic-human hybrid.
I have heard and read about both nephelim on this view and about human clones that they cannot be saved or even have no souls. This seems to be false.
Book of Baruch says that the giants of old did not find wisdom "not one of them" - suggesting they could have found wisdom if they had looked better. But being able from the start to get what you want by domination over humans of lesser stature and powers is not a good starting point.
In fact, if Goliath was nephelim brood (through one of Noah's daughters in law), so was St Christopher. And when I call Christopher a "Saint" I mean it is known he is saved and in eternal glory, it has been shown the Church by sufficient miracles.
As I brought up clones, a clone would probably be the person of the emptied human embryo, but with the wrong genes for this person. This kind of mismatch might make for difficulties of harmonisation as with - if such be possible - angelic-human hybrids, but if difficulties were bravely faced with a sense of decency overriding monstruous temptations and with a hope in Christ, yes, such a person could be saved.
That does not mean the 200 angels had any right to such an "adventure" (if that is what happened), or that anyone making a clone today has such a right. For that matter, nobody has a right to make a child through rape either. But in these cases salvation is at least theoretically possible. If, as is suggested in book of Henoch, none of the children of the 200 were saved, this is not because God did not gave any possibilities, but because God arranged that the ones refusing those would coincide with among others all of the original Nephelim. To punish their fathers.
If there were ever Nephelim totally uncapable of salvation, as opposed to merely rejecting it, this is because they had no souls, because they were biological machines. But in that case one may say the fallen angelic fathers had no real biological equipment for making them either.
Such a thing should not lightly be assumed of anything resembling a human. In cases where a woman gives birth to what one does not quite recognise as human, there is the possibility of conditional baptism: "If thou art human I baptise thee in the name of the Father, and the Son and the Holy Spirit". Precisely as there is conditional baptism for people when one is not sure whether they were previously baptised or not.
No creature ever was predestined without a test to damnation. No angel was damned without sinning or before sinning. No man was damned before Adam's sin. And no man who reached the use of reason was damned without any sin of his own.
What is sure is that giants seem to have some capacity for honest if not sophisticated basic wisdom like the one showed by St Christopher after he converted. And thus for salvation too. And one hermit getting to visit another, in the Egyptian desert saw a faun crying over the idolatry Egyptians make of fauns, as if sure he was meriting damnation merely for being its object, even if not willingly. More stupid than rotten if you ask me (but then I am a Narnia fan). In fact, not even all that stupid if he realised idolatry was a damning offense. And that it is at least not good to be cause of such in others.
Bpi, Georges Pompidou
St Raphaël the Archangel
*But there is not just the genes, there is the chromosomes they are packaged in too. Between man and chimp, just for "human chromosome two" it is not just that it corresponds in general to two chimp chromosomes (which evolutionists love to explain as its being the result of a fusion of them), it is also a question of in total 13 chromosomal changes (cross overs of arms, relocations, inversions of certain stretches etc) on top of the 100.000 differences for the loci of the genome. And apes have 48 while we have 46 chromosomes, which means there is not such a very great difference on the chromsome level as between man and goat or man and horse.