A study conducted by Pew Research Center found that US Internet users aged 12 to 17 dislike blogging and services like Twitter aren't too popular either among this age group. Full details at Guardian.
Blogging, on the other hand, may become more and more of a side issue. In fact, among all the content creating activities the decline in blogging among teens and young adults is striking as it looks like the youth may be exchanging "macro-blogging" for microblogging with status updates. Since 2006 blogging among teens has dropped from 28% to 14% and among young adults (aged 18 to 29) by 24% to 15%. Some 11% of those aged 30 and over now maintain a personal blog, and 14% of them maintain a personal website.
They don't really like to use Twitter, though. While 19% of adult internet users use Twitter or similar services to post short status updates and view those of others, only 8% of 12- to 17-year-olds do so.