Just curious why my portrait automatically uploaded?

Let me get this straight:

I just sign in as a totally new account and soon find out my portrait is already there!
and it’s EXACTLY THE SAME ONE I’m using right now on a Chinese public blog.
I turn to my friends and they all got a default portrait.
So what happened? Did the Codecombat use some mystery magic and somehow got my photo online?(I did my search too,no matching photos)
PLUS i never register Garvatar/Gmail or sth mentioned in profile page.My QQ.com email during register is all the info I gave to.

Some feedback is highly appreciated.

It’s based on Gravatar, so I think the Chinese public blog you’re on must also integrate with Gravatar.