Question: What if Adam had Repented?

Okay, so this is not just a simple question, but rather two questions (each potentially raising many, many other questions):

1. What if Adam had just confessed and repented when the Lord came a callin' in Genesis 3?
2. Or, what if, immediately after Eve partook of the fruit, Adam had said, "No thanks, we're not supposed to. Serpent, get away, and while we're at it, Eve, why don't you confess and repent"?

Would the course of human history be different? If so, how?