I am part of a family that has had the wanderlust gene.
This is what I wonder - it does seem to be very much genetic. I know a few families similar to my own, where they are continuously on the move. We don't have to follow the food anymore, we can choose to follow the heart.
It also does not hit every person in the family, I am the only one in mine to live in so many diverse areas, the rest are all still with in 50 miles of where we grew up.
I count your niece among the lucky to have inherited it. It is nice having family that stays in one place or area, always a fall back option for stability, but the urge the need to see different and far away things is strong in the entire family, some just see it through our conversations and letters back home, but the whole family travels with and has a place to visit when one of us hit the road.