I would suggest that our teens would be better off if adults would offer them guidance in how to handle sexual relations responsibly, given the exceptional potential they can hold for interpersonal strife, rather than simply declaring them off-limits until a certain age and then assuming they're mature enough to conduct themselves responsibly, except that it occurs to me that most adults probably aren't competent to offer good advice on the subject even if they were willing to discuss such matters with teenagers.
I once saw someone on the Internet proposing that ability to consent should be granted after an exam, rather than after a given age, much like we don't grant everyone who reaches a certain age a driving licence.
You want to make it easy for people to know whether another person has the legal ability to consent. If consent is about whether the person had taken an exam, it would be hard to know.
A twenty five year old woman who doesn't want to have sex before marriage for religious reasons could simply avoid taking the test. People who take the test before getting married could be expelled by the local church.
The proposal seems to give fundamental Christian's a ugly tool for charging people who engage in premartial sex with rape.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.