Age of consent, drinking age, smoking age -- I think the state should leave parenting in the hands of the parents. I dislike the idea of the "underage" being treated as second-class citizens.
In May of this year, Canada raised the age of consent from 14 to 16 as part of the initiative to "stop internet predators." I think the public associates consensual sex with victimization when dealing with a young adult and an older partner. Where in the instance of choosing is a victim made? Whether or not a 14 or 15 year-old took advantage of his right to sleep with an older partner before, I think maturity comes with responsibility -- not with sheltering and coddling.
In his book, Stephen Colbert jests that children should be given arbitrary rules and not reasonable ones -- that way you're teaching them discipline and not reason. I think children should be taught reason and not discipline. Making an informed decision, I can easily see how a young adult could reasonably argue for his right to become involved with an older partner.
On the other hand, in my city right now, a young adult is currently taking advantage of his right to put an older partner in jail -- because the age of consent isn't simply 16, it's 18 when a "relationship of trust and authority" exists between the teen and the adult. Apparently a 16 or 17 year-old's earned judgment in choosing a partner is clouded in that instance. A teen is not mature enough to clearly choose under the sway of authority until 18.