I look at it this way. Most kids are going to have to experiment when they get away from mommy and daddy. Most of us did it to one extent or another. My daughter's going through this right now (she's 20). I've let her know I'm not happy with what she's doing, but she is an adult and she lives on her own, so technically, it's none of my business.
LOL - and I used to believe parenting got easier as the kids got older. Boy, was I wrong! (22 yr old and 19 yr old twins)