I was born and raised in the northeastern U.S., which will always be "home". However, I had many foreign-born relatives, friends, teachers, classmates, and neighbors, and had German and Spanish throughout high school and college. I came to Germany, a country which I had visited a couple of times, on a Fulbright scholarship at the age of 22, and met my husband (German) less than a month after getting here. We married in Germany, but went (back) to the U.S. for about two years for job reasons. When I was 25, and he was 30, we returned to Germany (my German has always been better than his English, and he had an excellent job offer from a former employer), and have been here ever since. We brought a 13-year-old Siamese cat (my childhood pet) and a 3-year-old Boxer back with us. Transporting pets overseas is nervewracking! Neither one ever learned German, but come to think of it, Jamie, who was born here, ignores German, too.
He was fostered by a French family, and then came to live with us. I'm 49, and since I spent that year here as an exchange student, I've now been living abroad for literally half my life.
Since I understand the language and culture, and can make myself understood, I've never experienced the "culture shock" so many people talk about. Sure, there are differences, but I find just as many differences between Philadelphia, my "hometown", and Omaha, where what is left of my family is now living. Going from living in a large city to living in a small semi-rural town was more of a "shock".
I miss seeing my family members and old friends on a daily basis, but it's so easy (and cheap) to keep in touch nowadays. As a teacher, I get a 6-week summer vacation, and have the luxury of being able to spend 1 month a year with my family, as my husband is willing to "hold down the fort" here.
I agree with Eithne that it's harder to make friends as an adult than as a teenager. I have a few close friends here, but they can't replace the friends I've had since I was in middle school. However, I'm not lonely - it's hard to be when you're surrounded by people (teaching colleagues, students, in-laws, neighbors, etc.). Many of my colleagues are also foreign-born, and married to Germans, so we have very special bonds, regardless of whether we're from the U.S., Canada, Britain, Ireland, France, Spain, Argentina, Peru, Russia, and so on.