2 Nephi chp.2
22 And now, behold, if Adam had not transgressed he would not have fallen, but he would have remained in the garden of Eden. And all things which were created must have remained in the same state in which they were after they were created; and they must have remained forever, and had no end.
23 And they would have had no children; wherefore they would have remained in a state of innocence, having no joy, for they knew no misery; doing no good, for they knew no sin.
What this says to me when I read it is that
if Adam had not disobeyed God's command:
1. He would have lived forever.
2. Lived that forever in the garden.
3. Lived in the same state in which they were created (If I recall correctly, God said it was very good by the way)
4. Lived forever knowing no sin.
5. Would have had no children.
6. Continued forever in a state of innocence.
7. Never would have known joy.
8. Never known misery.
9. Never done good.
10. Would have never known sin.
This tells me also that the marriage bed would be impure or In other words, sex inside the context of marriage is sin.