Growing Up

Does anyone else reach that point in life where they take a look at themselves and don't really like what they have become and/or how they treat others? Since when did my social decency, etiquette, kindness, and concern for other's feelings become nonexistent?
Seriously, how does one change so much from childhood? The loss of innocence and naivity definitely has something to do with it, but I believe there is more to it than that... I'm not quite sure what it is, but a change must occur that I am unable to pinpoint. Is this good or bad? Is it that big of a deal to transition from what your personality was earlier in life? Is what you become simply "the new you" or are you able to redeem some of those brilliant qualities that vanished slowly so many years ago?

I really just don't know.