The Great man theory emphasizes on the inherited qualities of a leader. It says that a leader is born to lead. It claims that the leadership qualities of a leaders a evolved along with his personality under the influence of the environment and people that he grows up with.
This theory can be often right, but not always. The history of the world is full of lives and systematic order of successions of the royals families of past centuries from across the world. Every prince was born to lead, every prince was groomed and trained to become the finest king or the leader of the people. However, no state is recorded to have more than one king in one period. This fails the Great man theory on certain realistic grounds.