If you want to know if someone is "real" tell them an obvious lie. A human will recognize it for what it is immediately, a cursed will not. They may look real, but they are not. Only real eyes realize real lies.
Griffin decides to move his family to Mexico when the hostility in Mansfield doesn't stop. A negro boy is helping Griffin pack up his parents house when they get to talking about racism. Griffin tells the boy nobody is born racist, but taught to hate.