When I turn 18, do my parents still have any legal rights over me?

Legal control, no. They may still have fiscal control if you are still dependent on them for food and shelter.

Because most states consider you an adult at 18 technically No they do not have control over you. That does not mean that they have to support of approve of your choices in life. It also means that they have a perfect right to ask you to leave or move out if those choices do not meet their approval. It is a two way street here. My girls made decisions and as long as they were good decisions about their futures I supported and helped them 100%. If they had made In my opinion bad choices, they would have been asked to get out of my house in about 10 seconds.