The children of Catholic parents aren't automatically Catholic - they become Catholic through baptism, indoctrination, participation, and so on. Those children may choose to stop being Catholic at any point in their lives. So it is with any other faith. I've often said that being a Witch isn't something that you do, it's something that you are. The answer to these questions is both simpler and more complex than most people think.
Witchcraft is based on paradigm or worldview.
Research has shown that humans and animals are predisposed by their genes to exhibit certain behaviors. This is still a controversial idea, however I believe that our genes govern some of what we do. Certainly, our environment contributes a great deal to the way we look at things. The way we were raised and the things that influence us have a direct affect on our worldview. Like changing an old habit, we can work to have a different perspective.