I'm thankful that I had the opportunity to spend most of my teenage years learning web dev, programming and tinkering with technology, instead of catching up with fashion trends and doing other teenage shenanigans. Unfortunately I rarely ever went out, and the result is that I've entered my twenties and I don't know how to carry a basic conversation.
I'm pretty sure it's not a personal problem, as I've never been diagnosed with autism or the like, and I am a very professional communicator by email. It's just that I struggle to respond to basic social cues, read people's emotions, know what to say, and to talk loudly and clearly. The only exception is business, which I can generally handle decently. As soon as it becomes informal however, I become a train wreck of awkward, and am very conscious of it. I especially struggle with saying something without thinking; I need 5 seconds to think over my next sentence, and people give up on me.
I've heard Bill Gates can be pretty unapproachable; is there really something about being mathematically minded which makes us socially different? How does one learn basic social skills after "growing up", has anyone done it?
The dad drops this little bit of thought-technology his way (and apologies for the mangling of the quote):
"Here's what you do, alright? First off, you gotta ask her a lot of questions. Then you have to listen to the answers, alright? Actually be INTERESTED in her, alright? If you can do those things, you'll be LIGHT YEARS ahead of those other guys."
Ask a lot of questions and be interested in the answers - that'll go a really long way. Remember, everyone's got a story and I think everyone (in some way, shape or form) wants to tell it.
Also, practice socializing. This stuff comes really naturally to some folks and really NOT naturally to others. If you're in the latter camp, practice like you'd practice anything else you want to get good at. One of the local user groups I frequent has what it calls 'socialization practice' after each meetup. It's just everyone heading to a pub and hanging out, but it's a pretty good way to get to know people and practice some of these softer skills.
Best of luck - you can do it :).