User blog comment:BlackWizardZeref/Fairy Tail: Chapter 380 Hell's Core/@comment-76.124.155.27-20140413200702/@comment-24546844-20140414184034

My teory is the simplest one: Natsu and Gajeel aren't over a hundred years ago, but theyr magic is. As the magic is part of them they're not allowed to pass. Maybe the dragons left part of their souls in their sons with the magic so that would explain a lot.

I have more problems with the fact of Natsu's scarf being death-magic proof. If Igneel made it then he knew Natsu would fight Zeref someday wich makes me think about the true role of Igneel to the plot. And why the other dragons didn't left any special present to their sons.