Prophets are born of men and women the usually way. Many Prophets grow into the gift, although the desire, even the capacity to prophesy is given before and at the time of birth. A person, man or woman will grow up the usual way and then on a given day, God may just start to talk with them; They may hear the voice of God and simply began to follow the voice. A person may be born with night-sight, known as a dream or day-sight, visions while one is awake.
Because God has already determined pre-birth, and has gifted a person to be able to speak forth the future, prophesy, a person becomes aware of the propensity to "know" things before they happen or may dream of events, only to find out later that what was dreamt, has come to pass. After the first, second, even the third occurrence of this, a person simply begins to pay more an to that gifting, than their normal overt daily lives; then the gift of the prophetic will grow and flourish.
If God is calling a person to an expansive prophetic calling, a person will be brought into even more relational, exclusivity, so that there gifting is not hindered by common daily distractions, affairs of daily life that will cause dissipation to the process of prophetic growth.
A clear example of the prophetic development of a person can be read in the story of Samuel; [1 Samuel chapters 1 thru 7.] In this story can be seen the story of a man's total immersion into prophetic life; before, during, after his birth and into the totality of his human life, unto death.