How do I help my teen daughter understand why porn is bad?

[Charles B]

You might not approve of porn, but it's one of the more benign things your daughter is being exposed to. Movies and TV programs depicting violence are much more harmful. I restricted my daughters access to violent entertainment. You know, all those "John Wayne" and "Dirty Harry," types glorifying shooting, killing and beating the hell outta some one. I never objected to entertainment with love making and/or nudity. My kids never got pregnant, had drug problems, or had problems with the law. They all had 4.0 GPAs and were popular socially. They all grew into responsible, contributing, members of society. Do you actually know of any harm that porn causes? Outside of extreme agitation from helicopter mothers??