It took a few minutes to come up with three backgrounds tied to existing 5e Dragonborn Lore, and with reason to be in Baldur's Gate.
I think you all are missing @Hussar , please correct me if I am wrong, main concern with this Dragonborn tangent. Hussar already has said its perfectly easy to come up with a reason and work with the DM to place his Dragonborn in the setting. The concern lies in that, despite being a typical PHB species, the the books generally offer no reason for the DM to include Dragonborn in most locations. This means the player playing the Dragonborn will never be able to tie their backstory as deeply as another species to the setting/story locale. Always being an outsider or at best a single household that maybe first or second generation. Rather than picking from an assortment of preexisting groups in the setting like the Flaming Fists or the humans/elfs of the Dead Mire.