That's the problem in a nutshell. The central message of Genesis is ethics, not genetics.
Genesis is a reliable record of Horite rule and the Kushite expansion out of Africa. It is more about the origins of Messianic expectation than it is about origins of humanity or ethics.
I teach Ethics on the college level and I agree that Genesis provides a unique ethical viewpoint. In fact, the binary worldview of Abraham and his ancestors pervades the whole of the Bible. The superiority of one of the entities in the universally observed binary sets prevents the Biblical worldview from slipping into the dualism that characterizes most Asian religions and philosophies.