If you are adopted, you must request an application for a certified copy of your birth certificate in the state where you were adopted, using your adoptive name. If you were born outside the United States and adopted in California, there is a place to indicate this on the birth certificate form (and this might be the case in other states).
When you were adopted in the Unites States, your birth certificate was changed to reflect your adoptive information—whether you were born in the U.S. or not—and your original birth information was sealed. Therefore, the existing birth record will have your adoptive information. ↑
Cal. Dep’t of Public Health, Application for Certified Copy of Birth Record (Form VS 111) (Jan. 2014), http://www.cdph.ca.gov/pubsforms/forms/CtrldForms/VS111.pdf. ↑