This is difficult to answer and of course it doesn't have to be one or the other.  My own experience with teaching is that there are a few 'naturals' who seem to pick it up more quickly than most.  It is exceptionbal to actually keep records of teaching and learning, but in recent years there have been quite a few studies, mainly related to understanding the development of language in our early ancestors.  I was funded the the Leverhulme Foundation to do just this sort of research.  My co-investigator was Dr. Dietz Stout of Amory University, Georgia.  My part was the teaching and learning and his was coordinating the neurological aspects of the study.