Self-discipline and control would be one thing that cannot be taught by anyone because if the person really wants to do something they will do it no matter what happens, no matter what advice that you are going to give to her. They are the ones that would help themselves as well, if they really want to have that kind of characteristic, they should learn to limit first themselves and know what to prioritize.
Yes, in this way I believe most of the aspects of trading could not be taught by anyone so that they will become a perfect trader all of sudden. I mean all the aspects of trading should be learned by own so that it will be possible to become a practice in their trading. If we study something just from books then that will get forget when we are trading. But, when we are experiencing something then that will be definitely remembered while trading. This is the difference between being taught and learning by own.