I can relate to so many of the moments already described, but the first inkling came when I was about 20. I've always loved science and was so excited when the bright turquoise "Creation" book was released, especially since so much of it was backed up by REAL SCIENCE in the form of QUOTES. In particular, Carl Sagan's book Cosmos was quoted, something to the effect that the fossil record could be consistent with a Designer. Only, I looked up the actual quote and found that it was a partial quote, that what Sagan was really saying was that the fossil record was consistent with a capricious, unpredictable, destructive kind of Designer. Not exactly what the WT was saying. I was able to stifle my shock and carry on like a good minion, pioneering for years, marrying an elder, until I was in my late 30's and I thought--I need to look into that again. I started researching everything about creation vs. evolution, Noachian flood, etc. and well, when you actually start looking at real science, everything pretty much falls apart.
This site was invaluable as well, as Leolaia was posting then, some truly scholarly and eye-opening stuff.