There is a legal answer to this and a practical answer. Legal answer: Age of consent varies around the world from age 13 in a few countries to. Washington, DC – Are teens most likely to have their first experience with sex in the back seat of a car? Or in their own home? Between the time. Read An Excerpt From 'The Real Truth About Teens And Sex' Do you have a secret about your sex life .. to digest, from the standpoint of protecting teens, it doesn't matter if parents know exactly when they start having sex.