It's not a 1-1 mapping but it can narrow things down to you and maybe a handful of others. If you're doing something like file sharing repeatedly over several days/weeks they can pull data for all of that time and when your IP is the only constant they'd know it was you. If they have only a handful of people it could potentially be, and they care enough they can seize and search the devices of everyone to find the person.
Also, you don't have to be logged into google for google to know who you are. If you're using windows, your OS is also phoning home constantly with identifying data. If you use steam, it's also phoning home. Run wireshark sometime and see how much your computer is sending to random servers without you doing anything or being "logged in".
Also, you don't have to be logged into google for google to know who you are. If you're using windows, your OS is also phoning home constantly with identifying data. If you use steam, it's also phoning home. Run wireshark sometime and see how much your computer is sending to random servers without you doing anything or being "logged in".