Parents need to start disciplining their children in young age because folly is bound in the heart of a child.
Proverbs 22:15 says, "Folly is bound up in the heart of a child, but the rod of discipline will drive it far away." New Living Translation says, "A youngster’s heart is filled with foolishness, but physical discipline will drive it far away."
And here's what The Message Translation says, "Wise discipline imparts wisdom; spoiled adolescents embarrass their parents."
Again, let me quote here Proverbs 23:13 NIV: "Do not withhold discipline from a child; if you punish them with the rod, they will not die.Punish them with the rod and save them from death."