It runs in your family. Maybe not your siblings, but your mom or dad and then from there. For me it starts at my great grandmother on my mother's side of the family, then grandmother, then my mother, then my younger sister and I.You are right that it is rare. Although my sister's abilities are not developed, I know based off our childhood. We seen ghosts while my brother seen nothing. I know a few as well, and I guess they're lucky since I prefer isolation. I've asked them questions and they said yes without knowing what it related to. Surprisingly they both have deja vus. Maybe empaths gravitate towards each other unknowingly.