Proverbs 22:6
Train up a child in the way He should go: and when He is old, He will not depart from it.
Notice it says, He should go...
There is a way a child ought to go and when the child doesn't go that way, he would be walking on a path not prepared for him or her.
This way is the Word way.
This must be done early so that it becomes a part of him such that he knows nothing else but the Word. The Word of God becomes his guide.
Psalm 119:105 says, Thy word is a lamp unto my feet, and a light unto my path.