No they don't, by saying this I'm pretty sure you are one of two things. You're either a 15 year old, or you're a child enthusiast.
I am 15, and many people my age already are already going to extreme parties and having relationships already and doing other things involving their bodies. A lot of teenagers have an idea of what they want. In many countries people get married at 15. Mentally, emotionally and physically we aren't kids. It's pre-adulthood.