I find relatively few atheists that, like me, were born atheist and stayed that way. I am curious to know how many of us are out there and why we never picked up theism from our various upbringing.
To me, an atheism is one who knows about religion and has consciously rejected it. What you are describing is the absence of belief simply because one has had no experience -- either way -- with it. They are NOT the same.
I was raised in a devoutly Catholic family. I was sent to all the catechism classes but at 5 years old asked to be put up for adoption if god was my father. That did not go over too well - lol.
I'm one of those few. Of course, it's relatively few, because the vast majority of people around the world believe in some sort of higher power, and pretty much half believe in a monotheistic god. Atheist or secular families are relatively rare. My family is one of those. I went to a Church of England private school, but none of it really stuck; by the time I went there, I was old enough to think critically.