Emerson described "<em>genius</em>" as a person's individuality. He dafined it with these words:
''To believe in your own thought, to believe that what is true for you in your private heart is true for all men, - that is genius.''
So we can learn that when a person accepts and embraces his/her individuality, that person exhibits genius.
Hope this helps! God bless :-)
The most inclusive answer would be their. As his or her has binary limits and we do not use its to refer to human beings.