Mark Zuckerberg quotes and aphorisms about you Mark Zuckerberg ,, Really, who you are is defined by the people who you know - not even the people that you know, but ... Mark Zuckerberg Mark Zuckerberg Mark Zuckerberg Mark Zuckerberg Mark Zuckerberg Mark Zuckerberg Mark Zuckerberg Mark Zuckerberg Mark Zuckerberg ,, Think about what people are doing on Facebook today. They're keeping up with their friends and fami...