Adam and Eve would have had children over a span of hundreds of years...for someone in “batch one” to marry someone in “batch three” would not quite be the same as for you and I to marry the sister we were raised in the same house with. It is simply incomparable...
Cain and Able would have been the product of a man and his clone?
The Genetics here would be pretty weird
I suspect that this is a mystery that will be revealed in due time
I accept the Genesis account at face value,
I just don’t understand some of it