When it comes to the Book of Concord, there are really two types of people: those who read the contents and see a series of rap albums, and those who aren’t Flame.
Repentance comes on account of suffering, loss, failure, and death. It happens when the promise of forgiveness of sin given in Jesus’ death is proclaimed to us down-and-outers.
Yes, Adam and Eve both participated in sin. This was a joint effort of the two genders of mankind. They are both sinners. But the first sin wasn't letting the serpent in the garden.