We are essentially creating a characterization for our selves by the content we place here, by the titles we choose, the topics we write about (be they political, literary, artistic, domestic, etc.). We suddenly have an audience, even if it’s only a few people. With an audience, we are sending out a message.
When I was teaching writing, I had my students do self-portraits in words. This was a great exercise for college freshmen to do, and it was my favorite assignment to grade. The kids took all kinds of creative risks, which was one of the points.
I never did the exercise myself. Perhaps this is it.