Proverbs 22:15 (ESV)

15 Folly is bound up in the heart of a child, but the rod of discipline drives it far from him.

In Scripture, “folly” (or foolishness) is not innocent stupidity, but rather a condition of sinful rebellion against God. Sadly, folly is already bound up in the heart of a child. When Scripture speaks about the heart of a human being, it says that “every inclination of the heart is evil from childhood” (Genesis 8:21; cf. Psalm 51:7; Job 14:4).