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...