Basically, around 2012 I created my current SO account. I have since had an email change, as I became locked out of my yahoo email account, and so I started using the Google email associated with my Google account - the one Google, by default, creates for every Google account holder. I tried to log into Stack Overflow with the google email, and it created a brand new account. At first I was freaked, because I had worked up what (to me) was a decent amount of rep on some sites, and it appeared that somehow my (relatively) inactive account had somehow been pruned from the site.
I eventually discovered that SE creates a new account for each email. Is this intended behaviour when you log on with Google? I was under the impression that it is supposed to be 1 account/Google account.