"at that time the human body was in the original form (created to last forever, before the fall, before vast generations of degeneration) and siblings reproducing with each other was not what it would be currently."
What empirical evidence do you have to support this assertion?
It is not about empirical evidence. It is about faith. It is about spiritually discerning that which is spiritual. It is about reading the entire Bible (and not just once), not just selected passages, not just reading about the Bible, not just relying on others to tell you what is in the Bible and what it means.
My broader point was that when marstegreg said ‘I could never figure out how Cain and Able found women to marry when there shouldn’t have been any’ and thought ‘Genesis had too many holes’. He assumed that according to Genesis there were no women, but he did not understand because he had not read the whole Bible enough to get it, probably had not even read Genesis itself: I mean, he even was apparently under the impression that ‘Able’ found a woman to marry when one major tenet of the Bible is that Abel’s whole line was cut off by Cain’s killing Abel out of jealousy. I just added the part about why siblings reproducing back then would not have been the big problem it would be today and to not assume that would not have happened back then just because these days it would be a problem.
Anyway, you may not really get what reading the Bible is all about if you are wanting someone to give you empirical evidence (from observation or experiment) from the Bible.
I would read the Bible for you if I could, but that is not how it works. It is the Living Word. It is on faith.