I did not choose atheism. I did not choose no religion either. I just was raised completely without the concept of religion or gods, no theism at all. No one I know (friends/family/relatives) is religious or believes in a god or something. We did not even touch religion in school.
Of course I heard about gods and churches and stuff, but when I was little, I almost never heard "it's god's work" or the like as an answer for my questions. Just a couple of time someone more or less unknown came up with something like god created earth and and dead people go to heaven and so on and so forth, and I was like "damn that man must be 40 doesn't he know we were on the moon there is nothing up there, what is he stupid?"
I never understood how a grown up person seriously could believe what was obviously wrong to me, a kid, and I also never understood that someone with problems would rather waste time to pray and whatever, instead of just dealing with it. That's also the reason why I never ever considered to "seek religion" later.