To be honest, I’m finding Tumblr a little confusing. Everyone has these cute site names and no one has an email address and I don’t really know which of you are in high school and which are 45 years old. (Though I know which of you have babies and/or are alcoholics, because parents and alcoholics talk about their obsessions equally frequently.) Still, so far, any confusion is well overmatched by enjoyment. I give Tumblr a strong B+, and an expected good score on its midterm will bring it to a solid A-.
The age issue is the most vexing. I can only suggest that you don’t go looking for what you don’t want to find.