Middle is Middle right?

Americans would like us to believe that there are three social classes: upper class, middle class, and lower class. We like to think that being put into a social class is easy, but in reality, where is the line drawn for each class?
The hardest class to be ranked in to me, is the middle class. Even though someone could be making 20,000 a year and another could be making 50,000 a year, they are still considered to be in the same social class even though one is making considerably more than the other. That's harsh.
Besides the money factor that determines what social class someone is in, there is also a certain subculture one must follow in order to be accepted into that class. Take for example the upper class. They all talk a certain way, dress a certain way and are a certain way. Even if you are at their party in your finest and you are middle class, if you don't walk the walk and talk the talk you are screwed. They are going to see right through you.
I used to think that class structure was all mental. That if you wanted to be in a certain class, if you worked hard to be upper class, you could. Sure that might be true in some cases, but the majority of cases don't work out that way. Unfortunately, you're class determination starts before you were even born- it starts with your parents...and that means there is very little wiggle room as to what class you can jump to.