Volusia County Public Library discussion

Many characters in A Song of Ice and Fire would jokingly refer to a Targaryen being mad, or insane, based on the gods flipping a coin. However, was there an actually biological reason for some of this madness. Targaryens, as Valyrians, were different from other races of humanity. They could tame and ride dragons, and were often not affected by extremely high temperatures. Could this, plus their practice of incest, have created some instability in their DNA that would surface from time to time? Or, perhaps, because of the roles they took in life, where some Targaryens driven mad by how they were treated by others. Rhaenyra Targaryen started a civil war over being passed over for the Iron Throne, and later generations looked upon her with scorn. Was she born mad, or did the betrayal of family and others drive her to it?