No.
Everyone is naturally social.
We lived in social groups for 100s of thousands of years. It's genetically built in us to have a predisposition to socialize.
The reason certain people grow up to be less social then others is due to experiences growing up. Being mocked in a group situation and not having a strong emotional safety net to fall back on, etc. People who are more social once they get into adulthood, had the experiences that reflect either being accepted easily into social groups or when rejected had a strong emotional safety net to fall back.
Basically it comes down to conditioning. Using statements like "Oh, he's just not naturally social", to excuse introverted behavior and in thus further engraving this pattern of behavior as not only acceptable in the child's head, but that it's the right behavior. Could be as simple as parent trying to emotional protect their child from "cruel children" who pick on their kid. When the opposite should be happening, the child should be taught to have strong self-confidence and reintroduced to social environments.
Growing up all there lives this way, people view it as being natural. So it's natural to avoid situations which would help you pass on your genes? Yeah, don't think so. Your body exists for the simple reason of being a vessel to pass on your genes. And you can't do that sitting at home playing Halo 3 all day, because you are just naturally introverted.
However once old enough, anyone is capable of turning themselves into a 'social person'. All it takes is recognizing what is wrong with them and then realizing only they have the power to change it.