I grew up homeschooled. The only time I did any kind of socializing with more than one kid at a time was church, and even then only sunday school. Almost every saturday growing up I spent the day with my best friend. It's surprising how hard it is to have friends and socialize when you don't go to school and aren't old enough to drive.
When I got a bit older, but still didn't have a drivers license. I was able to do some kind of socializing online and had some online friends.
Needless to say, by the time I was really able to socialize and had something the got me out of the house and around other people (a job). I wasn't exactly in a confident, healthy state of mind and able to socialize well. For one thing, I didn't have much as far as social skills went. I wasn't horrible at it, and probably better than I would admit to, but still I wasn't that great.
And spending so much time all alone when I was a kid, without much to do and a lot of time spent pacing around bored, didn't help me much...
So here I am. Friendless, and unable to make any friends, whether face to face or online. Things only get worse.