For a more in-depth story about Coster-Mullen and his pursuit of the A-Bomb, check out this New Yorker article published in December 2008.
Bummer I didn't get any responses to this. Clearly I should have included more invective and name-calling.
But, from what I've seen, an awful lot of folks who are doing home schooling aren't interested in exposing their kids to much of anything. They're more concerned about sheltering their kid either from harm, or from opposing viewpoints.
I'm married to a former teacher who is now homeschooling our two children. We're involved in a large homeschooling community, so I get to see lots of different homeschool types and what they're involved in.
My experience is that, in the vast majority of cases, these children are involved in many, many activities outside the home with their peers, partly for the simple reason that they actually have the time for extracurriculars (e.g., we can accomplish more in three hours of homeschooling than I ever accomplished in seven hours of "standard" schooling as a student). These extracurriculars cover the entire spectrum from science clubs to sports to writing and art clubs to you-name-it.
Now, I'm just as likely as anyone to snicker at the goofy homeschooler with all the awkward tics up there winning the National Spelling Bee, but I think there's often a lot of confirmation bias at play when folks paint with a broad brush as you've done. Sure, there are the weird goofy kids who homeschool, but, man alive, I knew a heckuva lot of weird goofy kids when I was in school too. And a lot of the socialization that goes on in public schools is not so positive...conformity, peer pressure, bullying, all sorts of groupthink. Let's not pretend that these are essential experiences for our children, or that positive socialization is unavailable or unsought after outside the public schools.