I learned this, by setting up a Disqus ID. I wanted to comment on a blog post, and started to set up an account.
After I started the process, it came back, with a list of random posts, from around the Internet (and some, very old), and said "Are these yours? If so, would you like to associate them with your account?"
I freaked. Many of them were outright troll comments (I was not always the haloed saint that you see before you) that I had sworn were done anonymously. They came from many different places (including DejaNews). I have no idea how Disqus found them.
Every single one of them was mine. Many, were ones that I had sworn were dead and buried in a deep grave in the mountains.
Needless to say, I do not have a Disqus ID.
Being non-anonymous means that I need to behave myself, online. I come across as a bit of a stuffy bore, but I suspect my IRL persona is that way, as well.
That's OK.