Prehistory of a Jackmormon
Here was my answer:
I had a somewhat different experience growing up in the church, and from my handle, you'll see I'm not practicing these days.
My father was not a member; he was a scientist and an atheist. My mother, on the other hand, had the maiden name of Smith. But because the religion and culture went so far back, was so deeply entwined with her family identity, she wasn't particularly interested in theological problems or exact obedience.
We went to the ward my mom had attended for decades, in the town she grew up in. It was a small ward in a mostly secular university town. My father characterized the congregation as the "newly wed and nearly dead." Most of my Sunday School teachers were graduate students. My teachers emphasized that the terrestrial kingdom was like earth and that the only punishment for these sinners was to be far from God; one year was marked theologically by two lesson plans, one on Milton as proto-Mormon, and one on the old paradox of "If God is good, and God is all-powerful, why is there evil in the world?" One of my teachers got me a subscription to Sunstone when I was about 14, warning me that it might not be a great idea to talk about reading the magazine. At the time I had no idea what the problem might be because my church was harmless to the point of inanity, the members uninsisting to the point of grandmotherliness.
When I went to summer camp, however, I mixed with Mormons from other wards and found a very different culture. Initially, I was jealous: these other young people attended wards with lots of other young people! (My average Sunday School class had about three students on average.) Over the years of attending these (admittedly short) summer camps, I began to realize that what I experienced there was more typical of the Mormon experience--and I didn't like what I saw there. Tearful exhortations against abortion (whereas I had never considered having sex before marriage), whispered late-night conversations about spirit-possession, in general, a much gloomier version of the religion I had grown up with as a cultural given.
I don't want to give the impression that Mormon summer camp was the factor the clinched my decision to move away from the church, but it was my most important exposure to the broader culture of the church when I was growing up. My rather insular ward was very inclusive, nurturing, and scholarly; the broader church structure I encountered in my teens seemed more prohibitionary and anti-intellectual.
Anyway, there's a data point for you.