I don't know that anthropometry is involved. A short back will lean forward more in the overhead squat, but when the weight gets heavy everybody drives hips up anyway. I think it has more to do with upper back and shoulder flexibility, and why the limitation is persistent. An uninjured kid learning the lifts should be taught to squat snatch because it is more physically efficient. But it's not more efficient if you CAN'T do it, and you need to know when this is the case.