Magnet has no pull

At a small high school's graduation ceremony, five kids were graduating from the same big family. The great-grandparents of this family would always attend the ceremonies for the later generations. A guest speaker asked the principal of the high school, "How is it that the five kids in this big family could escape the traps of where they live, while other youngsters at this school couldn't?" The principal pointed out into the audience where the great-grandparents were seated, replying, "When a brick wall is in front of a magnet, it has no pull."