If God can do anything can he make a mistake?

Well he knew his father Leopold who was a composer but i can`t remember if he was an opera composer or not. So at least 1 composer. 


As i am not an intelligent man i have to admit i am not sure what you are trying to argue here, It seems to me that you are saying because Mozart was a genius and could compose at the age of 6 that somhow is an argument for God.

Of course i could be wrong.