Because I've met several homeschooled adults over the years, and talking to them that's something most of them had in common when explaining the impact it had on their life. Looking for more objective data I found this one source that seems to be written by people not already convinced of the desirability of homescooling [1], forgive me for being skeptical of the objectivity of places called "national home education research institute". Overall it paints a more positive picture than I had expected, but also highlights it's limitations.

[1] http://hks.harvard.edu/sites/default/files/Taubman/PEPG/conf...

From those slides (I did have to open them via google, the direct link didn't seem to work):

  Discussion
  • Evidence from this study and others suggest that homeschoolers may not
  be a socially isolated group
  • Instead, homeschoolers in these samples seem to have peer networks
  and social connections that arise in conventional and unconventional
  social settings and they report being well-connected later in life
  • It is important to note that although this study contributes to the
  literature, it has methodological limitations (e.g. small sample, self-reports)