In the early days of the first Skeptics in the Pub meeting, when there were only 20 to 30 of us attending, we used to talk about this a lot.
Many of the skeptics around then used to claim that they were born skeptics. They didn't ever believe in Santa, had worked out that God didn't exist before they were 10, etc. I can't claim any such thing myself.
My drift into skepticism was very gradual. At a young age I read Science Fiction. This lead to also reading woo. By the time I was 14 I'd read Lobsang Rampa, George Adamski and loads of other bollox. Von Daniken was the big new thing. Initially I believed it all because it was in a book. The more I read the less I believed. The different books contradict each other, they're always claiming a breakthrough is just around the corner (even in an old book I picked up at a jumble sale), etc. I became more cynical and sceptical but retained an interest. I read the Fortean Times and went to their first convention in 1990ish. By this time I was pretty much a skeptic but was not part of the skeptic movement and didn't call myself a skeptic. I just sat there laughing at the loonies claiming that alien abductions were real, moon landings were faked, etc.
It was only meeting Skott Campbell at SF pub meetings (2000ish) and his decision to start a Skeptics pub meeting that exposed me to the skeptical movement proper. Not that it changed my mind about anything, I'd got there all on my own.
I find it interesting that some Skeptics are now less interested in reacting to the loonies who promote ghosts and UFOs and there's a move towards distancing ourselves from woo. It still seems to me that the point is to shine the torch of reason onto woo, not ignore it.