You were born in the US but are 100 percent Polish when you visit family in Poland they say you look and act different then Polish people living in Poland why is this?

Your genetics does not determine your personnality, your environment does. Poland is very different from America. So you dress and act like an American, not like a Pole.
If you speak Polish really well, spend a lot of time in Poland, and work hard at it, you may eventualy learn to dress and act like a Pole who grew up in Poland.