Factors affecting the genius

The genius could be distinguished into variable groups, such as math genius, literary genius, or music genius. I would concentrate on the music ones.

The musicians, like Mozart, Beethoven, attain impressive capacities to hold many pieces of melodies. For instance, Beethoven could hold five, six, even seven melodies at once. In addition, they could compose elaborate music without playing or hearing. For these ones, they are really gifted ones.
On the other hand, they would not do well in their fields if they spared any endeavor. For example, Beethoven spent his almost all his life on music. Even though he became deaf at the end of his life. He never discarded the music, but insisted on what he devoted to. Without this persistence, he would not succeed.