I don't think that clothing shapes us at all. In my opinion it's what's on the inside like our personalities, decisions and experiences that make us who we are. I mean, if there is someone who is really mean and everyone thinks that they are a bully, then chances are that they're still going to be a bully whether they are draped in old rags or wearing the latest Abercrombie sweater. What I'm trying to say is that a piece of material can't do anything to shape you as a person.
However, clothing is a way to express yourself and people can tell a lot about you from what you wear. For example, if you are a really outgoing happy person then you would probably wear bright neon colours rather then jeans and a plain, boring shirt. People definitly judge you on how you dress, somtimes this can be a good thing or a bad thing. If you are wearing really nice clothes then people might have more respect for you and if you are trying to make a good first impression for a job or university then nice clothes might help. The bad part of people judging you by your clothes is that they really do make first impressions. If a new kid walks into your class wearing the latest and greatest clothes, then a lot more people might want to be their friend. However, if that same new kid was to walk into your class wearing an old baggy shirt not as many people would want to bother getting to know them, even if they are always really nice.
That is why the clothes that you wear are important, but I don't think that clothes shape who you are they are a great way to express yourself, but it is your thoughts, feelings, decsions and actions that shape who you are.