In your family was siren blood being passed down since generations… Each family member had their own unique features like small scales etc… Yours was that you have a nearly angelic voice like a real siren does… it wasn’t really easy since you needed to avoid any kind of singing in your childhood but by now, you can control your voice… But nobody except your family knows about your siren blood… it also could happen that the older you get, the more features you develop…