I don't have my full name filled out on any site (including Stack Overflow which is my oldest site):
However, when I create an account on a new site (I've just done it on Money) my full name is filled out:
The rest of the profile information is copied from my Stack Overflow profile (as expected), but where on earth is getting my full name from?
A couple of things that may (or may not) be relevant:
- Stack Overflow has the Developer Story/CV attached so it could be pulling the name from there. I could temporarily change my name there and repeat the process to check.
- I'm a moderator on Stack Overflow, though I don't see why that should affect this at all.