At some of the early points of a childs development, say from the toddler stage, there is a benefit to the methods most jw's use that give their children an advantage. I've known many kids that knew all 66 books of the bible, could recite every story almost word for word out of the bible story book and make a pretty good stab at most of the names in the old testament. It needs to be said, though, that that comes from rote memorization which is shown to help with concentration, word association and eventually, reading.
If a parent or care provider that has no jw background would spend the same amount of time reading or having the child memorize words, numbers and pictures in something that has as much interest to them as witling propaganda does to witless parents, I believe that child would be just as far along in the same skills. "Okay, Tommy tonight's bedtime story is 'Mr. Jingles replaces a carburator'. Last night we learned how an internal combustion engine works. Do you remember the firing order for the spark plugs in a Chevy small block? Very good!"
It all seems to come down to willingness to spend time with a child.
Chris