"My son can come down from sleeping and recount his dreams in detail to me and then still remember them weeks later. Perhaps the differing sleep patterns between teenagers and older people mean fewer dreams?"
As @twizzle mentioned, I think everybody dreams at night. But I don't think the problem that some people can't quite remember their dreams the day after is a little bit more complex than just a problem of short and long term memory.
I think the problem lays at the imagination level. Teens and children have more imagination as they don't know everything about the world. Sure as adults, we only know a portion of the knowledge of the whole world, but way more than children.
And that's probably the larger problem, we don't trust everything we see. Be it on TV, the Newspaper or any other media.
Maybe because we question things more than children and don't trust everything we see, our brain might dream, but think "Hey, this can't be real, let's forget it".
Occasionally, I can remember my dreams. Maybe I should start writing them down. I read somewhere that if you write down your dreams right after waking up and you build a habit out of it, the brain starts to change and remember more and more details.
Also, Lucid Dreaming would be an interesting thing to try out. Has someone here experience with it or encountered a Lucid Dream?