I think that *anything* is bad for someone (teen or adult) if that person is not equipped to handle the consequences - teen or adult. Shoot, some of these men running around having babies all over the place (and the women letting them) - sex is bad for them too! And their adults.
When a teen is able to step out of his mommy and daddy's house, get a house of his/her own and raise a baby on his/her own w/out relying on someone to help (whether it be mommy and daddy or gov't. mommy and gov't. daddy) then teens should talk about having sex. When they are ready to face potentially contracting HIV, Herpes (which apparently is on the rise) and any other number of sexually transmitted, non-curable diseases, then maybe.
SC