I empathize with your concern. But it only takes one emotional indiscretion at a young age. Teenage hormones are very powerful. Many girls are not tramps, but are not as white as snow like their parents think they are.
I know about teenage hormones. I also know that most of my friends waited until college to have sex. Most of them didn't wait until they were married, but they were in college.
I think waiting until they are 16 and then seeing what they are like at 16 to see if we can wait until 18 is wiser than getting the vaccine too soon.
It's just not worth the risk at 12.
And does the risk that someone might make a bad decision really justify the government stepping in and dictating to people what they are to do and how they are to live their lives? For what? To protect them from themselves? Who's going to protect us from the government? And what if it turns out that there are unforeseen complications that result? What then? Guess who gets to live with THOSE consequences, and it isn't the governor who issued the order.