This story is ridiculous if you have any critical thinking skills. I tried to argue this with a religious friend of mine (also an ex-JW). He just gave me looks like I was stupid for not just accepting the story at face value.
Matthew 22:20 says that at the resurrection, there will be no more marriage because people will be like angels. Implying what? And all of the angels are theoretically males. So does that mean at the resurrection, everybody will have penises? Or that angels don't get married? Or that they're sexless?
I used exactly those same arguments. Hormones drive our sexual urges. Eunuchs aren't lustful because they don't have the testosterone producing organs. In order for the angels to sexually lust, they would have had to have hormones. Now why would God create them with hormones? And in an all-male population to boot? Or was gay sex OK among angels? That question got a dirty look from my friend. Furthermore, if the angels had sex but weren't allowed to marry (like in Matthew 22:20) does that mean they were living in sin?
My friend also believes these faked pictures on the internet of giant skulls and thinks it's proof of the Nephilim. And for more detail, he goes to the apocryphal book of Enoch. Which sheds more light on the story and goes into detail about the names of the angels involved, etc. Now this book was rejected as part of the Bible, but he thinks this is telling the story and believes it anyway.
But it puts the height of the Nephilim (the offspring of angels and women) at either 300 cubits or 300 els. And there's some debate on the length of an el and whether it was translated properly. But basically it puts the Nephilim at something between 300 - 3000 feet tall. Or about 50-500 times the size of a person. Which is way beyond the size of these fake skulls, so he's willing to take that as exaggerated - but not the rest. LOL!
And I argued the square/cube rule. Which basically says that for something that's 50 times taller than a human, it would have to be 50 times wider and 50 times deeper too. So it wouldn't weigh 50 times more than a human, it would weigh 50 x 50 x 50 times as much or about 125,000 times as much. So a 200 lb 6 foot man scaled up to 300 feet would weigh 25 million pounds. Which the cross section of those bones couldn't support. Basically there's a reason larger animals don't look like us. They have MUCH thicker bones. This Nephilim wouldn't be a man of renown, he'd be a cripple who couldn't stand up without breaking his legs.
Also, what's a baby? About 18 inches. Times 50 would be 75 foot tall. How is a woman supposed to give birth to a 75-foot tall baby?
The whole thing is ridiculous. Obviously thought up by men who were telling a tale as a plot point for a story. And 4 or 5 thousand years ago, it made sense.