My mother was raised in a "perfect Christian home." They didn't do anything wrong. And because my mother was so afraid of what her mother thought, she wanted to rise us in a similar manner. If she had had her way, we wouldn't know what sex is. We would think Christian music is the only music out there. We would have no idea what a "swear word" is. We probably wouldn't even fart; it makes us seem less than perfect.
My father, however, came from a broken, non-Christian home. Growing up, the only time he heard about God was when there was a damn after it. His mother was an alcoholic. He barely knew his father.
My mom tried to keep us sheltered from the world. And she succeeded for a while. My father, however, didn't like how ignorant we were of the world around us. So he made an effort to keep us from drowning in our mother's overbearing protectiveness. And once my older brother and I hit thirteen or so, we began finding things out for ourselves, by every means possible. It wasn't long before we were "ruined" in the eyes of our mother.
She's since withdrawn her grip on us a bit. She's come to realize there's no way she can control my older brother and me any longer. And she's also come to see that my little siblings won't stay innocent either. She still tries, yes, but isn't very successful. Partly due to the fact I want to make sure my siblings aren't as naive as I was at their age. Perhaps it's wrong of me, to let my twelve-year-old brother listen to System of a Down and Rage Against the Machine. Maybe it's wrong that I teach him that *gasp* liberals, homosexuals, and people who have abortions are actually people too (he's been brainwashed under our conservative household for a little too long; it's still taking me a while to convince him of those things). But I don't want him to be ignorant.
My sister... there's no teaching her. She's exactly like my mother, only more so. But I have hope for my brother yet.
It's not that sheltering your child somewhat is wrong. It's just that, if you overdo it, things may turn out the very opposite of what you wanted. My older brother and I went through some hard, hard times before we came to terms with the real world. I want to save my little brother that pain.