My particular kids don't, but among my first-hand circle of GT acquaintance of all ages, I know several who have had fascinations (cars, planes, buses, aquatic animals, dinosaurs, dogs, sports, etc.). I also know a few information omnivores, who don't so much have a rage to master a particular topic, as have a huge thirst for any kind of knowledge. Some of them are on the more reserved or socially-awkward end of the temperament spectrum, and others are more social. I have seen almost all of them socializing in a reasonably age-appropriate way when in the presence of intellectual peers who can keep up with the rate of their information processing, and appreciate their store of knowledge, even if they don't share a common fascination.
