Leadership qualities are inherent in some individuals, in others it can be taught, and in some these qualities will never show unless they are forced into a position where they have to step forward and lead. And there is a smaller minority that would fail even then.
The U.S. Military is a prime example of teaching people to be leaders. For decades they would take prospects who might be leaders and run them through various training courses to develop the skills needed. And that's just for peacetime. During a war often the leader steps forward from out of nowhere. He or she may well have been someone who was looked up to in the unit but who did not have a leadership position, but when those above them are removed from the scene of the battle, they step forward and take the duties and responsibilities and move the unit forward.
In fact, modern business with its emphasis on manager training is also trying to teach someone who may or may not be a leader the skills to become one in hopes that one will step ahead and out of the pack and prove himself once he has learned these skills.
Another way in which leaders can be made would be through the presence of conditions that call out for leadership qualities. In history, the emergence of leaders has been due to specific conditions that have necessitated leadership in multiple forms. Independence movements in different nations have created the setting for leaders to emerge. In America, the injustices of the British called out for a man like Sam Adams and other Patriots to assume the role of leadership. In the Post Revolution Constitutional Convention, the discord and dissonance which was present demanded people like Governeur Morris and Roger Sherman to emerge as individuals who could achieve compromise. Another opportunity present for leadership could be during the Civil Rights Movement, when the injustice of racism in American social and political setting called out for a thinker like Dr. King to assume the mantle of leadership. I think we can examine particular conditions in any nation's history and speak to how these help to create the moment where leadership (both in good and not so good forms) are present. Historical and social conditions provide the soil and nutrients for the plant of leadership to grow and mature.
The question of whether leaders are born or made is centered mainly around the question of weather the skills and capabilities required for effective leadership present in individual, or these can be acquired and developed by any one, irrespective of the qualities present from birth.
Irrespective of whether or not there are some essential physiological characteristics including mental make up, present in effective leaders from birth, one thing is quite clear that development of individuals including their psychological characteristics and their acquired skills play a very important part in effectiveness of leaders. For example let us take the communication ability. This is a very important skill needed by all leaders. Though some people appear have better aptitude to learn the use of language and other means of communication, there is no doubt that every one must learn to communicate through education, and improve the communication ability through practice. Thus some amount o" making" is essential for leadership.
This does not automatically mean that there are no basic attributes essential for leaders which are present in them from birth and cannot be acquired subsequently. This view is summarised in the saying "no amount of polish can change grains of the wood".
There is substantial evidence to suggest that successful leader tend to differ from others in many psychological and sociological characteristics such as attitudes, motivations, people orientation, aversion to risk and willingness to take initiative. These qualities cannot be acquired by class room education. But these does not mean that these are determined from birth itself. Many of these characteristics develop at an early age depending on each individuals circumstances and experiences.
May be about 50 years back, people did not know enough about how the personality traits conducive to effective leadership can be developed by individuals. But now substantial body of knowledge is available on developing such traits, This body of knowledge is growing further. Using such techniques and methods individual can be moulded to become effective leaders even when the are quite old. It is not easy, but it can be done.
In summary, I will say that basic individual characteristics for becoming leaders are not God given. Some basic personality traits for becoming effective leaders do develop at an early age, and are difficult to modify later. But by following right techniques and putting in sufficient efforts, these qualities can be developed by adults also. Thus it is possible to make leaders.