I wonder how humanity spread after the flood that wiped out humanity.Correct me if I am wrong, but does this mean that the descendants of Noah's sons Shem, Ham, and Japheth committed mass incest to proliferate mankind, since they were the only human beings left on Earth? This inquiry can also be applied to Adam and Eve's descendants after their banishment from the Garden of Eden, ironically said to have been located in Mespotamia or modern day Iraq. If that is the case, at what point was incest determined? It seems Sacred Scripture is not clear on this matter, but have the Doctors of the Church addressed it?
Also, I know that Shem, Ham, and Japheth represent the European, African and Asian(Middle East and Anatolian) peoples in the Old World respectively. How about the Native Americans in the Western Hemisphere and the East Asian peoples in the Orient?