It was The Phantom Menace and its associated EU material that marked the big change in the nature of the Jedi order. For the first time, we saw that the Jedi trained not young men, but young children, and it was expected that they would be severed from their parents. This is the first hint of the cloistered nature of the entire Jedi order.* It seems apparent that the parent-child relationship is replaced by the master-apprentice relationship early on.
Attack of the Clones expanded the lore of the cloistered Jedi. The Knights were now forbidden to have possessions, to desire things, or to have normal romantic relationships. Obi-wan does seem to have a non-Jedi friend in Dex the short-order cook, but he also uses Dex for information. Do the Jedi have normal relationships outside the order? (Edit: And who can forget the Jedi leaving Schmi Skywalker in slavery on Tatooine, to be eventually raped to death by Sandpeople? Evidently I could.)
Revenge of the Sith didn't particularly change anything, but it gave us a look at the effect this upbringing has on a young man. Anakin has found a woman he loves, is soon to be a father, and has developed an incredible and highly-marketable skillset. The only monkey-wrench in his life is the fact that the Jedi order forbids marriage and paternity (at least, it forbids active parenting; it may secretly encourage purely reproductive coupling in the hopes of producing more Jedi initiates). Any normal person in Anakin's situation would shake hands with Obi-wan, resign from the Jedi, and work as a highly-paid contractor or consultant. He could then choose his own hours, make as much money as he needs, and publicly enjoy family life. But Anakin never considers this course of action; his "sad devotion to that ancient religion" has constrained him so much that he cannot envision life outside the order, not even with all his advantages. He is stuck on the Jedi ladder, attempting to gain rank and influence over his colleagues at the expense of developing a satisfying, meaningful personal life. It's not surprising Darth Vader happened. It's surprising he didn't happen all the time.
I think I got on a little tangent there, but here is my conclusion. I have always thought that the Prequels attempted to show the "other side" of the Jedi; that was the only explanation for the generally stupid and/or malicious way in which they behaved. They were the same organization described in the OT, but we were now seeing a different set of their characteristics, through a different lens. Now I'm not so sure. Now, I think the Prequels show a completely different idea of what the Jedi were. The PT and the OT cannot be reconciled, not without throwing out significant portions of the canon or tortuous rationalizations**. I don't think that will bother many here, but it's food for thought, if you have a taste for this kind of thought.
*It reminds me all too much of any number of cults and terrorist organizations that prey on children, twisting their development and teaching them to use violence from a very young age. Surely Lucas was aware of the parallels?
**If you do want to make a tortuous rationalization, I think the metafictional one is best. The Journal of the Whills, or The Adventures of Luke Skywalker, whatever is the source text for the Star Wars saga, was written by different authors in different eras and certain discrepancies may exist. Which facts are "true" is a matter of debate.