My personal experience here is far tamer than many — as a straight white boy, for example, I didn't need to worry about getting beaten like the gay kids or followed around by the guards like the Mexican kids did when they went to the mall or library[2] — but I grew up in a conservative religious tradition and getting online where I had access to forums like the talk.origins Usenet group was key to realizing that the religion I was raised in was full of people I trusted who were telling me lies[3]. There was very little in the way of a technical community in the parts of California I grew up in but thanks to FidoNet and the early web, I was able to learn how to program well enough to get a hight score on the CS AP test despite going to school in two districts which didn't even offer the class, which mean that I was able to jump on board the web train as that started taking over the world.
1. Disabled, parent of a small child, kid in a suburb where you probably don't have anything within walking distance even there is a safe way to walk without getting run over, someone who lives in a rural or poor community without well-funded libraries or vibrant public spaces, etc.
2. One high school I went to was about 50% migrant farm workers. Seeing the difference in how those kids were treated was eye-opening – both the willingness to police them in ways which even the skater punks didn't get but also the tyranny of low expectations where it was just kind of assumed that they were going to be ground down by the system and should set their sights low.
3. Biology classes in school wasn't enough — the creationists are good at coming up with arguments to discount curriculum – but what really opened my eyes was seeing the full original source materials which were selectively quoted in the religious writing. It's possible to be innocently ignorant but there's really no good faith explanation for slicing-and-dicing a quote carefully to make it sound like some famous scientist meant the opposite of what they actually wrote.