> I didn't understand at the time and still don't know how they matched up my Google account to my Twitter account The information on http://www.google.com/s2/

> I didn't understand at the time and still don't know how they matched up my Google account to my Twitter account The information on http://www.google.com/s2/u/0/search/social http://www.google.com/s2/u/0/search/social can be informative for checking how Google links you with other people. Even if you didn't share your Twitter username with Google, I suppose that if someone on your contacts list shared their Twitter username, Google would be able to make the connection.