How did Google notify me of the birthday of a person I don't have as friends on any social network?

Question

Google

Of course, I suspected that corporations were watching us and all that, but ... Today, a Google calendar that I have never (!) Used notified me of the birthday of a person who is not my friend on any social network.
I myself could not put it on the calendar, because I got an android background in February of this year. Before that, the only Google service I used was gmail.
We have common acquaintances, yes, but they are not on the calendar...

Answer 1

Druzhban got a job at Google and was offended that you forgot to congratulate him that time.

Answer 2

If you have his phone number, then perhaps he linked him to G+ and google linked his number and the account in which d.r.

Answer 3

Look at G+, maybe he added you to his circles. You are not. My smartphone takes d.r. and adds to d.r. contact for example from skype. Most likely you cross paths with him somewhere, take a closer look.

Answer 4

Isaac Asimov. True love

Answer 5

Most likely it is in the recipients of your GMail mail.

Answer 6

And in the android background in the contact of the phone book d.r. registered?

Answer 7

Have you verified your phone number on Hangouts? If yes, then here is the result, by phone.

Answer 8

I myself sometimes wonder at the magic of Google))

Answer 9

can someone added in such a cunning way, if they have not yet closed the hole?

Answer 10

Synchronization for which services is / was?

Answer 11

Perhaps you are among his friends? Or he has an android phone where you are in the contact list. Or he has GMail, where you are in the contact list and / or to which you often send letters. Well, there are a lot of options.