...but I used to have a job where I would get a lot of demographic info on families - including where they were from, and where they have family.

This is a total stereotype - but it seemed like if someone was originally from Utah, they were likely to have nearly all of their immediate family members also living in Utah. Sure, now and then a black sheep would escape the state - but by far the majority stayed instate.

On the other hand, when I met a family from another state, it was very common for them to have parents and siblings that lived in more than one state. In fact, it was rare that they were in Utah and the rest of their family would be all living in their state of origin. Typically they'd be spread all over.

Just go me thinking that people who stay close to home, tend to have immediate family that also stays close to home. And people who move away, also have immediate family more prone to move away.