To explain nurture vs nurture, I always use the alcoholism example. There is a strong correlation between genetics and alcoholism, but if there is no alcohol in the environment, the individual can never possibly grow up to be an alcoholic. As with introversion, nature and nurture must come together to form this trait. I think personality is flexible, in some instances we are all introverted and in others we are extroverted. But the lifestyle itself isn’t a bad thing, as long as it isn’t maladaptive. If the person is so shy that they miss opportunities at school or work or socially with boyfriends or meeting new people, then it becomes a mental problem. But if the person just would rather spend time alone and it doesn’t cause them stress, then more power to them :)
