Well as others have stated - Dragons do indeed have genders now. Though I dont know they were intended as "genderLESS" (not the same as asexual) brecause the early answer was always more related to "only dragons can tell" so to speak. But no at least now, NPCs refer to male and female dragons.
However, when it comes to "where baby dragons come from" - asexual or genderless does NOT mean you can't reproduce. So..you still have wehre baby dragons come from.
As for death and reborn - thats from the lore. The "Gifted" of Istaria got that way because they died to their mortal life and were reborn as gifted. So basically, technically by lore, every player character has died and been reborn to be gifted.
Whether that negates their ability to have children is up for debate, but it does suggest that hte lore argument for gifted having children - is that the children may not be gifted as they didn't die first.
Its why many of us (esp. us early lore people who didn't have asmuch lore as now and only a few truths - the Gifted thing being one of them) have death-stories of our characters "before being Gifted" and then a rebirth scenario. Its also why, for example, Frith-Rae "lost" her entire family when she was reborn because they either did not die or were not reborn as Gifted (at the time It was not clear that gifted shared the realm with non-gifted so I honestly thought everyone, NPCs included, running around in istaria were all gifted).