When you allow a fresh set of eyes on your admission essay it is almost as if your personal statement is getting practice. After all, your statement will ultimately end up being read by one or more people while your application is being reviewed so it makes sense that a well read personal statement should do better in its final stages. Why have the reviewers catch the mistakes that someone else can catch beforehand? It is far better to catch a small mistake that can cost you admission, before it actually has the chance to cost you.
In conceptualizing a theme, you have to consider the main question, "What would you like to say with your essay?" For example, do you want the admissions committee to understand your choice of major and career in relation to your family background, or do you want to share your passion for your chosen field and your desire to achieve excellence in it? Whichever theme you come up with, this has to be unique to you as an applicant and should be related to your personal background, choice of major, and choice of career. The more unique a theme is, the more interesting the essay will be. In this sense, you can capitalize on personal facts you believe are noteworthy of exposition.