It takes a certain aptitude; some of it is natural talent and innate understanding, but the rest has to be learned through practice and study. That sort of natural talent came easily to me, even though I didn't understand all of the principles behind it - what I was working with as a child were very simple, basic transmutations that didn't require a high level of skill or a lot of comprehension to carry out. However, I wasn't one for traditional study, and I soon fell out of practice with it; it caught my interest again when I was a bit older.