I agree that Jesus’ interpretation seems to be clear. We’re speaking of individuals, some who are God’s children, some the devils. But you know how it is with parables… He who has ears to hear etc.
If a person born of God doesn’t sin (1John5), then presumably a person born of the devil does nothing but sin. However, I see neither sort of person in the real world. We all seem to be a bit of both. If many (most?) people are in fact born of the devil, how would this devilish paternity transmit? By what rules of spiritual heredity? In one family, you might have 3 unbelievers and one believer, all from the same parents. How does it work?
I find it helpful to think of physical dimensions. Just as there is absolutely nothing North about going East, there is nothing good about evil, or evil about good. However, a person moving North-east is moving both east and north simultaneously. In the same way, I find both good and evil in myself simultaneously, expressing themselves in everything I do.
I thought of another example last night. I am both rational and irrational simultaneously. When someone reasons with me, they are speaking only to the rational me. The irrational me cannot understand a word of what’s going on, and rejects the entire conversation with disgust. Similarly, when someone speaks the truth about God, the spiritual me hears and understands, but the unspiritual me does not. The word of God “rings true” only to that part of me that’s in tune with God. It resonates.
Re. the nephilim etc, those stories occur in a thoroughly mythical context. We have the creation of the world, magic trees, talking snakes, cherubim, fiery swords, towers reaching into heaven, giants in the land, and angels fathering mighty children from mortal women. Though I firmly believe those stories are inspired and profoundly true, I think they are true like the parables of Jesus are true, and that we cannot get reliable scientific information from them. That’s not their purpose.