Not at all. It is intellectually amateurish to conclude that everyone literally descended from Adam or Noah as the result of incest. There is no evidence of that, only assumption. It is very simple theology that God creates who and what He wants, and does not have to report His every action to His creation. Anyone with a brain can appreciate this concept. Simple logic can postulate that there were other people on Earth aside from Adam and Eve, they just happened to be the very first ones. I've heard there's a verse in the Bible that they went to another location on Earth and found people there. Mystery solved. Same with Noah. No reason to assume any incest was involved. Surely as God can create the heavens and earth and all creation, He could manage to create a few more people to avoid incest being committed, no?
It's all quite simple really, but then there is the issue of people who start their thinking process with an anti-religious sentiment (mostly created by decades of cultural programming which portrays religion in the worst light) which assumes that religion and religious thinking is backwards.