On this D&D Legends and Lore, William Stark and Omar Timsah cover the lore of Dragonborn.

Perhaps no other peoples of the worlds of D&D better exemplifies the darker side of society than Tieflings. Not the “darkness” of their own appearance or demeanor. Not the darkness of their fiendish heritage or the dark magic of the lower planes that is their purview. But the darkness of society’s reaction to them.