The most important statement in your question is "What's behind the headline..."
Let's split this up into two questions:
First: are teens doing cool science?
Teens, like anybody else, can do science. A lot of teens are actually in a good place to do really creative work (scientific or otherwise), because they're young, have relatively few responsibilities, and are brash enough to try things that will probably fail. Sometimes, those things don't fail.
In some problems, it's easy to get to the edge of science: my favorite example is the iGEM genetic engineering contest. Another great example of an "easy" problem is how cats drink water: that's a paper in Science whose key laboratory equipment was a good high-speed camera---the key innovation was how they thought to ask the question, and it could just as easily have been a teen as a bunch of folks as MIT (though the teen would have a harder time getting it published so well). Other problems, though, e.g., "prevent cancer", are really pretty hard to do anything about.
A good heuristic for understanding what's going on in a particular case is to look at how much background and resources is required in order to take a particular approach to a problem. The more that's necessary, the more likely it is that any teen involved is a small (though possibly still quite smart and creative!) part of a big organization.
They also might just be wrong. Lots of ways to be wrong in science, for teens and anybody else. You should judge the science of a teen just like you'd judge the science of any other researcher.
Second: Do the headlines have much to do with what teens are doing in science?
In a word: No.
In a few more words: science reporting is often pretty dismal, and in popular sources usually has much more to do with fitting something into a societal narrative. And one of our cherished narratives is the Teen Genius.
Also, don't forget that both teens and their mentors are just as capable of being self-promoters, self-deluded, or frauds as anybody else.
Bottom line: if a headline sounds like one of those terrible "One weird trick..." internet ads, it's probably about the same level of reliability.