As children, we have no understanding of what God would do in our place. We are not born with a belief in God, let alone a knowledge of how he is. We do not even have the ability to apply the secular definition: we are not born acting consciously. It takes time for us to develop the capacity to think, act, and reflect on those actions. It takes time for us to begin to observe the world and make judgments about what we perceive.
Children cannot sin until or unless they arrive at the ability to understand value. Only then can they choose to act in a way that is less than their understanding of ideal.
Until or unless children arrive at the ability to understand value, they are absolved from the penalties of sin by the atonement of Jesus Christ.
For everyone else, arrival at accountability coincides with their choice to sin:
For all have sinned, and come short of the glory of God; (Romans 3:23)
As all men sin, all men require repentance. However, the sin we are responsible for is our own, not the sin of Adam and Eve.
Too many Christians distort the concept of sin by couching it in the choice of Adam and Eve to break God’s command and eat of the tree of good and evil in the garden of Eden.
The impact of sin on an individual has nothing to do with Adam and Eve outside of providing an environment where you could make your own moral choices and thereby commit sin.
The idea of original sin is a clever way to get people not to accept responsibility for their choices. By reducing any accountability for sin to the fall of Adam and Eve, too many religious leaders have— intentionally or not—excused individuals from recognizing that they are capable of sinning or not sinning. It’s difficult to adopt the idea of accountability for someone else’s choices without feeling a false freedom from accountability for our own. Religions amply teach that a person’s sin lies beyond their power to choose. This is wrong.
We are not held accountable for Adam’s sin in any way except that we all die physically. The sacrifice of Jesus Christ overcomes that penalty. We are held accountable only for our own choices.