High school. You never really leave it. If you're lucky, you move away and find a new circle of friends who didn't know you then. Assuming you have your act together now, you can dupe them into believing you were always a competent person - unless you write a novel that exposes every flinch-worthy moment of your teenage stupidity. Then everyone will know.
Do you think people will buy that disclaimer that the book is a work of fiction and any resemblance to people living or dead is a coincidence? Maybe I should add another line. "I'm much better now. Really."