One curious thing about Twitter…

… is that my younger sisters (aged 25 and 20 respectively, young enough that they won’t kill me for revealing this information) don’t care about Twitter at all.  Neither do their friends, and none of them use it.

Mind you, these are very tech-savvy kids.  They’ve grown up with the Internet and its various tools, they’re used to it, their whole loves are online.  I consider them more bleeding-edge than most people, technically.  I’m including their many friends in this consideration, too.
Years ago they stopped using email.  The youngest one barely even realized that her Facebook login is an email address, since she never used that funny-looking string for emailing.  They haven’t used email for maybe 3-5 years now.
Twitter, they never even started using.  Yet it’s all the rage in some circles, and I personally have been enjoying it as well.  Is it a reversal of the above pattern, where I’m ahead of them?  An exception to the rule?
Or is it that I, and others on Twitter, are technological dinosaurs just playing with a new toy because it’s “similar enough” to blogging and email that we’re familiar and comfortable with it?
Or maybe Twitter really IS that cool, and they just haven’t gotten it yet.  But it’s curious, to me at least.
Randomly looking around at people on Twitter, using various tools like TwitterGrader (a HubSpot invention), it’s hard to find anyone young (teen-agers, let’s say) on Twitter, at all.  I wonder why that is.