“”Heck, I would have liked to know more about who Cain, Abel, Seth (and any other sons) married in those early years.””
THAT would have been the mystery I wanted an answer to as well.
They married their biological sisters. And/or nieces so to speak.
Not as horrifying as it first sounds. First of all people were living for hundreds of years so they were hardly siblings like we grow up with like today. Secondly no genetic deterioration yet so genetic issues nonexistent.
Incest was forbidden by the time God gave the law to Moses. By then people lived our normal lifespan and there had been many generations so we were in the genetic downslide of negative mutations we continue today.
Women. Same as a today.
A simple way to look at it us folks lived longer. Had lots of kids, married their cousins and even sisters.
Abraham married his half sister, Isaac had more of his grandfather s DNA than his dad, then he married his uncles daughter....
DNA changes over time due to environmental factors, and those are due to a fallen world due to sin.
Jesus will return to reset it all to perfection.