A very value that a leader holds is charisma...I believe that charisma cannot be learnt, you are born with it, and mature with it. Some ppl may have charisma, but dont know how to show it, because they are too shy. There are certain characteristics of a leader that can be 'learnt' to an extent, but I think being a leader is something that grows over a long period of time. You cant just wake up one day and decide you want to be a leader, you have to be patient, set a good example, and make people realise that you are capable of being a leader.
In primary school, i was a nobody, by no means can i look back and say i was a leader, but as soon as i reached high school, the teachers, and my parents both made me realise what i had, so i allowed what i had to come out, in turn i have become a leader, school captain in fact.
Now im not blowing my own trumpet, simple answering the query, that is how i see it. We are moulded as leaders as we grow up, but we are born with the important qualities.