don't forget it could be largely attributed to modern diets evolving as the world moves forward alot of junk these days alot lacking many of the essential vitamins & minerals for both jaw development & to keep teeth straight. It's not neccessarily just the kids themselves but may also come through the mothers diet (or lack of) during pregnancy. Also kids are too fussy today with what they eat so many just end up getting fed what they want which i guess leads to inadequate levels of what should be consumed.
FWIW Evidence points to fat soluble vitamins A, D & K2 as being essential for both development of the jaw & palate. Quite simply many of these vitamins are lacking or below reccomended daily intakes in many peoples diet today.
