I don't know if I am my username. I usually use the same name on all the forums/internet sites i'm on (except it's a little too long for some sites). In fact thenumberthirteen is my second Internet alias, and I thought of it, strangely, while at the Cinemas watching Die Hard 4.0 (not that it was boring or anything)as there are quite a few people afraid of the number thirteen (known as Triskaidekaphobia)and so it sounded like a cool name.
Previously I went by the name freemind62 (my e-mail address and Youtube channel are still called that) which I got from a cheat for the game "Enter the Matrix" (which I liked more than most people I know did) plus the number 62 which I sort of liked the sound of.
My online persona and myself are not different in any way it's just a handy cloak of anonymity behind which to express myself.