The time when he or she understands life itself and discovery  the purpose for his existence, this is what makes a child be of value and it all begin at home and from childhood, you will b taught some things but obviously not all and until that child realises this and begin to learn how to live independently and still make it in life, this also requires wisdom, which is both an application from both the parent in helping the child got positioned to the right path and the likes child applying wisdom in every areas of life that got himself into.