I've seen it mentioned by a few on the forum that at some point there was a realization that had they not been born a JW, they never would've converted no matter how many times the JWs tried to study with them. This was my experience too, and I'm wondering how universal it is for those that were born-in but eventually left.
I think I started having this thought (more specifically that if I were not born a JW, I would surely have become an atheist by now) in my late teens. For a decade I lived with this thought popping up frequently whenever I had a moment to think abstractly about things or when I pondered cosmology, evolution or morality. But all the while I continued believing (or trying to) and praying (usually as a hedge) and attending meetings and saying all the right things. In hindsight my ability to empathize with the "worldly" people at the door who might have good hearts but would want nothing to do with JWs was probably a large part of my apathy towards the ministry.
Because of this nagging thought, a sense of relief accompanied all the feelings of betrayal, loss, foolishness, and anger that washed over me in the moment I realized that, without a doubt, I had been born into a cult. I knew at that moment that while I had been lied to, manipulated and exploited by everyone I'd ever cared for that I was also finally free to be honest with myself. I was free from having to ask something of others that I knew I never would have done myself.
For those that were born-in, did you ever realize that you never would've joined if not for the circumstances of your birth? If you did, how long did you live with that knowledge before finally and fully waking up?