If you accept the Noah and the ark story, are all of us descended from Noah and his family inbreeding?
I do accept the historical account of Noah and the ark. There is external evidence from other cultures in the same type of story as the Great Flood. It provides even more evidence that the Bible says is accurate.
But we are not all inbreeding because we all descended from the same person. Noah’s lineage goes the whole way back to Adam and Eve. After God started over with the flood and re-created all of the earth, Noah and his wife already had three married sons.
The genealogies recorded about Noah’s sons tell us that they created three different lines that spread out into different areas of the earth (Genesis 9:18-19 and chapter 10). With the spreading of the families of the earth to different regions, there was even less of a possibility of inbreeding because when the cultures mixed you have different possibilities between the three lines.
It’s not until the Tower of Babel that humans begin to recongregate in one area. Even then, the people would have been living together, exchanging different cultures, and perhaps marrying. Either way, God splits up the world into nations after the Tower of Babel (Genesis 10-11).
Through trade and interaction with these other cultures, the world grew more and more dispersed and all of these different groups could mingle. There is no reason to think that the genetic material from Noah is the only thing that still exists. Different environmental conditions allows for different nationalities and cultures. It would be no different than it is today.