In this series on psychological foundations from an applied psychological perspective, we focus this time on shame, guilt and sin. Shame, guilt and sin share that all three are strong motivators for behavioural change. However, we can respond to them in very different ways. In this article it is argued that original sin is a variant of guilt and misfortune, that seems unfair: how can a new born child be blamed for being born in an unbalanced world? Denial is a common reaction to original sin, while this form of guilt plays a major role in our technological ostrich policy.