What's in a name?

I was thinking the other day about names, and how we are defined by our name to a certain degree. Most parents have names already picked out for their unborn child, which to me seems odd. I'm the kind of person who cannot name something until i have seen it. Admittedly I have only named things like cars, pets and in my younger days, stuffed toys. I was just thinking about how what we are called is such an enormous part of our lives. There are many other people called Rachel out there, who are nothing like me, but they too are defined (I'm not sure that defined is the right word to use here) by their name. But it IS who we are. People who have been given nicknames that they use all the time then become so associated with that label, I guess it is, that we forget that they have real names. We get very defensive about our names. Like if someone spells it wrong, or pronounces it incorrectly. Why is this...? What it is about our names that we are so inclined to defend? Anyway...that was just some random thoughts that I had at about 3.00this morning!