They are not your parents, what do you do?

How would you react if you learned the people you grew up with were not related to you, and you had never been legally adopted?
Would you hate them?
Would you trust them?
Would you drop everything to search for who you really are?
How would you handle the situation?
Maybe you would just disappear, or maybe confront them.
Think about the feelings you have now. Would they change?