Since both justification and sanctification are the work of the Holy Spirit, parents should not expect of themselves what only God can do. God does not require results. Prov. 22:6 is not a blanket promise from God because if it were, the effects of sin could be wiped out by using correct child-rearing techniques; there would be no need of the atonement. Responses vary to God’s Word (parable of seeds). Parents must sow seed and prepare the soil the best they can, but the child has free will to accept or reject the seed.
Good parenting is an imitation of how God relates to us as His children. Parents have a large impact on the religious beliefs of their children. One study found that fathers who attend church at least three times a month, discuss religion at home, and are committed to their beliefs have sons who follow the same pattern. Fathers who do not follow these 3 things have an inconsistent impact. God Himself will take on the role of father when none is present (Psalm 68:5).
Parents can make mistakes and still be successful.