I'm wondering what some of you believe that CAUSE of underdeveloped jaws to be. I don't believe it's oral posture. Not at all. Facial structure is marked at birth. IMO much depends on the nutritional/ physiological health of your parents' germ cells prior to conception. Or it could be genetics as well... but these problems seem to manifest a lot more in modern societies than in traditional/ primitive societies.
Therefore, I think much of what we call 'genetics' is multi-generational decline in nutritional status, i.e. compromised nutrition in one generation after another after another... and that's what you call "genetics" or "we don't know what causes it so we say genetics." For example, the health status of your great grandparents when they conceived your grandparents has a great deal with how healthy/ developed you will be; it doesn't necessarily mean if YOU had great nutrition growing up or had excellent oral posture that you'd develop normally... it's a trans-generational phenomenon. (unless someone can really convince me of the mouth-breathing hypothesis, but I'm doubtful). Moreover, just because a defect takes time to manifest itself doesn't mean it's due to something that YOU personally did wrong, e.g. nutritionally or physically, etc. Your craniofacial developmental plan is laid out at conception, and it just so happens that it takes time for defects to unravel and manifest themselves.
More specifically, does anyone think one of these physiological effects of degenerated nutrition (or physiological effects by some other cause) seems to be growth hormone deficiency ? I was just reading this article
http://www.angle.org/doi/pdf/10.2319/011905-17 and it turns out GH has a big impact on ramus and mandible length and some impact on maxilla projection as well.
Thoughts?