Do you have reason to believe they are not your biological parents?
Finding your biological father or mother is a strenuous and complex process. Ask to see your birth certificate. It will have your biological parent’s names written on it. DNA test is the scientific method to find out the real parents.
Please remember that Parents are not always the ones who gave birth to you, but they should always be the ones who love you unconditionally. Something’s are our strong believe;ie; an acceptance that something exists or is true, especially one without proof is a belief.