Many of us only know a small sample size of home schooled kids, and in our very limited experience, we find that those kids are a bit off in one of more areas, and stand out as having one or more social issues. Perhaps they wind up as better adjusted adults, I don't know, but they do seem to have some trouble fitting in as youth.
Perhaps their parents are perfectly fine with them not fitting in, perhaps they encourage standing out and being different as a sign of being better than average.
As one poster said, our own kids sometimes make us cringe, so it is not a condemnation of home schooled kids, just an observation based on our own personal small sized sample.