Truly, a witch is born, not made.
Ly De Angeles (Witchcraft, Practice & Theory) writes regarding "being a witch":
It's in the blood, no matter how many generations it may not have been acknowledged (and self-preservation may very well have been why 7 or 10 or 15 or more generations ago your ancestor shut up about it and did not pass the knowledge down the line). Like a dormant seed, it waits until the season is fertile for it to germinate.
Of course, R' Avraham Abulafia has written that "every soul is a witch" [R' Aryeh Kaplan, Meditation And Kabbalah, p. 103]. Consequently, the work is to liberate one's inner witch.