Moralizing in Education

One of my favorite educational posters regarding drug use reads as follows:

Don't do heroin.
...
If you do heroin, don't share needles.
...
If you're going to share needles, (instructions on how to clean needles between each person's use).

In some school districts, education topics such as drug prevention and sex education have a lot of controversy surrounding what facts teenagers should know, and what they shouldn't. Somehow, there is this idea for some that the more you hide from a teenager, the less they'll have to actually confront in their social lives. This idea is illustrated with the idea that if comprehensive sex education is taught, teenagers will be more likely to have sex and contract STDs and get pregnant.

But in reality, beating kids over the head with the idealistic and patronizing message of abstinence only education just deprives teens of tools that will help them when they are confronted with very frequently-made and real decisions about having sex, doing drugs, etc.

Sex education has become more comprehensive over the past 50 or so years, according to this study of sex ed from 2006, there apparently was a decrease in comprehensive sex education over the past 10 or so years. Why would we be allowing this to happen?

One fact I find particularly interesting is this tidbit:

"More than nine in 10 teachers believe that students should be taught about contraception, but one in four are prohibited from doing so."

If educators want to teach youth this type of useful information, I don't understand why schools should have to yield to the wishes of authoritative parents or other figures that pretend to know what's best. How can we hold on to our moral convictions instead of what the facts show us, when teaching from a strictly moral standpoint leads to actually increase the dangers teenagers face?