FizzingWhizzbees said:
If you believe that those factors make it more likely that teenagers are going to have sex, doesn't it simply strengthen the argument for ensuring they're educated about how to protect themselves?
It strengthens that argument, as well as the argument to stay abstinent. I simply say you can't have one without the other. Ultimately, it is many things. I won't exactly weight them by importance, but I won't overly narrow it down to one factor. Perhaps I can elaborate.
Peer pressure: Let's say everyone you know is "getting a piece", and even though you live in a protective household, you're still jealous, and curious of what you may be missing out on. More than likely, you're going to hear about who "did it" than who "got it", as in a sexually transmitted disease or a pregnancy. I don't think this pressure goes away even in adulthood. Let's say you're on a business trip with your company. You want to remain faithful to your spouse, even though your buddies at work are thinking of hitting strip joints and possibly sleeping around.
Denial: There are plenty of sexually active people out there who don't want to get tested. Between friends of mine - an ex-couple, there was a case of multiple STDs. Of course both of them have done their share of sleeping around, and both have contracted STDs. If neither had gotten tested, and went on with this, who knows how many they would infect. Denial is very dangerous, a sexually active, temporary bedpet may ask if these people have STDs, and they are likely to say "no" because they don't know, and don't want to miss this golden opportunity. As you may have heard, 1/2 the people who have AIDS don't even know it yet. I wonder how many of them are sexually active...
Bad Parenting: Let's face it, it exists. A wide range of porn actors/actresses especially, chose their profession as a way of leaving behind or fighting back with sexual abuse they have encountered in the past. We should all be aware that within that industry, they have had their scares with STDs. I wonder if there are "you and me's" out there who don't have that profession, but are very sexually active with multiple partners in order to receive some kind of healing. Of course it's not always the case of sexual abuse, it can also be the lack of concern on the parent's behalf, or they are too hesitant to confront their kids about the risks of being sexually active (this coexists with our educational system, and perhaps a dosage of Maury or any other talk show may fill you in about this).
Pop Culture: Most movies that exceed that PG rating are at least going to have sexual references, some perhaps sex scenes, but whether they intend to or not, they promote sex. It may be their intention to stay in the bounds of responsible adults, but the message is going to reach those who are thinking of not only becoming sexually active, but plan on dozens of partners. The sexual messages are also big in music, TV, and radio.
Education needs to teach the benefits of abstinence, but also how to protect yourself with condoms, etc. There are two sides to the story, I tend to take both of them. Abstinence should not be abandoned, it should be encouraged. Protection needs to be taught, because obviously sex ed is not going to stop a long list of people from becoming sexually active.