My son was pretty much raised in the 'truth', despite the fact that I had turned my back on it. (I know...how could I do that to him? There is a story there, but let's just say I thought I was doing the right thing at the time). There was a year or two there around the age of 8 and 9 that he was overly zealous. He turned 16 today. We talk about it a lot. I am amazed at how much healthier his outlook is then mine. He simply says he doesn't believe they have it right, he's not really sure what is right, but the whole JW thing doesn't feel right to him. I don't see any scarring.
I do think that having some strong influences that did not buy in was helpful. I wouldn't consider him to be overly skeptical. But he was attending meetings with his JW grandparents, and going home to his two moms. I have to believe that when he compared the two styles of leadership, he preferred the one that encouraged him to think for himself and make decisions based on his own observations rather then dictated by an invisible god through autocratic elders.
So maybe that is a piece of it. I wasn't really encouraged to think for myself. Everything was fed to me, and questioning was discouraged. Perhaps, somewhere along the way, questioning opens up the world of possibilities.