Who has the power to decide?!

How is it possible in the 21st century for someone else to decide who I am, or who I am not? Does the "universal human right to self determination" as declared by the United Nations not apply to me? Am I excluded from this declaration?

How does one become what or who he or she is? Is it the government that decides? The priest, the church, the United Nations…? Who has the power to decide ethnically and nationally who I am, what language I can speak, what songs I can sing, what dances I can dance,…. And if anyone has that right who has given it to him or her?

I am Macedonian - Period. 

P.S. for more info about the dispute between Macedonia and Greece click here.