Great question. This is something my friends and I have talked about a lot. A million other people grew up in the same conditions but never became atheists, so why me? Personally I think it’s intellectual curiosity. Mormons are raised to obey power structures uncritically (this is one of the reasons why they make such good CIA piggies), so if they come across something that contradicts their leaders or worldview, they turn their brains off. When I came across info like that I just wanted to learn more, which led me here.