Homeschooling doesn't mean you're being sheltered. If you seriously think that just because they are taught by their parents mean they don't actually know anything about the real world, you're just useless to even discuss this with.
It doesn't absolutely mean the kid is sheltered but in most cases it's just what happens. We just had a transfer in our school come in as a Junior after being home schooled (As a high school student), and he seems to be not the most social kind of person.
The problem with homeschooling is that if the child doesn't do enough socializing on their own then they don't really develop the social skills that a real school provides (mind you, "skills" such as starting conversation, confidence, etc. not habits i.e. drinking/etc.).