I was raised as a witness and my parents were zealous witnesses. As a very young child I found going to the meetings, which were longer than they are today I believe, family study, field service and long assemblies completely bored me. I witnessed at school and was spoken well of by the teachers and later the same was true when I was an adult. But the boredom remained and the thought of an assembly or meeting was, oh God I've got that to do.
However I can't think of something that I didn't know of before I left. Some things may have come out after I left.
We had the book Jehovah's Witnesses In The Divine Purpose, I knew of the house in California and things like that. About a year before I left a brother showed me something in the Watchtower that bothered him it didn't bother me. Nothing would have made me question the society or the anointed.
1919 was the reason that these things didn't matter and it wasn't until I read something in the Watchtower that made me question the teaching regarding 1914 and subsequently 1919 that ultimately made me leave.