Maybe your parents don’t know either. They’re just covering all their bases. What if you were kidnapped from another family and switched with the baby they had, at a park or something- while no one was looking? Maybe your parents went through the whole changeling movie and just decided to put it to bed and accept the circumstances. This probably brings you no peace, but to be honest; it doesn’t matter too much if you did or didn’t, they’re still your parents for better or worse. (I look almost exactly like my mom, so I know I’m hers, but it’s not a warm thought if it makes you feel better)