In some ways, this mobility has become part of the natural course of a life. The script is a familiar one: you move out of your parents' house, maybe go to college, get a place of your own, get a bigger house when you have kids, then a smaller one when the kids move out. It's not necessarily a bad thing. Even if we did stay in one place, it's unlikely we would ever have the same deep attachment to our environment as those from some South Asian communities do. It just doesn't fit with our culture.
But in spite of everything -- in spite of the mobility, the individualism, and the economy -- on some level we do recognize the importance of place. The first thing we ask someone when we meet them, after their name, is where they are from, or the much more interestingly-phrased "where's home for you?" We ask, not just to place a pushpin for them in our mental map of acquaintances, but because we recognize that the answer tells us something important about them. My answer for "where are you from?" is usually Michigan, but "where's home for you?" is a little harder.
If home is where the heart is, then by its most literal definition, my home is wherever I am. I've always been liberal in my use of the word. If I'm going to visit my parents, I'm going home and if I'm returning to Chicago, I'm also going home. My host parents' apartment in Paris was home while I lived there, as was my college dorm and my aunt's place on the Upper West Side, where I stayed during my internship. And the truth is, the location of your heart, as well as the rest of your body, does affect who you are. The differences may seem trivial (a new subculture means new friends, more open spaces make you want to go outside more), but they can lead to lifestyle changes that are significant.
Memories, too, are cued by the physical environment. When you visit a place you used to live, these cues can cause you to revert back to the person you were when you lived there. The rest of the time, different places are kept largely separated in our minds. The more connections our brain makes to something, the more likely our everyday thoughts are to lead us there. But connections made in one place can be isolated from those made in another, so we may not think as often about things that happened for the few months we lived someplace else. Looking back, many of my homes feel more like places borrowed than places possessed, and while I sometimes sift through mental souvenirs of my time there, in the scope of a lifetime, I was only a tourist.
I can't possibly live everywhere I once labeled home, but I can frame these places on my walls. My decorations can serve as a reminder of the more adventurous person I was in New York, the more carefree person I was in Paris, and the more ambitious person I was in Michigan. I can't be connected with my home in the intense way South Asians are in Sax's book, but neither do I presume my personality to be context-free. No one is ever free from their social or physical environment. And whether or not we are always aware of it, a home is a home because it blurs the line between the self and the surroundings, and challenges the line we try to draw between who we are and where we are.