Both. There are born leaders and there are people who are not natural leaders, but step up because they see a job that needs doing or a group that needs motivating. Often the style of leadership of born leaders is more charismatic, but people who fall into a leadership role by choice or fate, can be just as effective.
I've seen this in practice when my son became the Senior Patrol Leader of the Boy Scout troop. He was following a very charismatic leader, which was a bit intimidating, but he stretched and grew and did an awesome job.