I wonder why the notification of my earning a "yearling" badge came in triplicate (three identical notifications). I haven't seen this type of behaviour before on StackExchange.
This is the screenshot:
If look closely at the logo for the site associated with the badge, you will notice that it is grey, and thus does not refer to Academia, but to Academia Meta:
This is also reflected on your meta profile. So apparently, your account on Meta was only “woke up” yesterday, but since its reputation and creation date is taken from your main account, you became eligible for there Yearling badges at this moment.
It is normal that you gain Yearling badges for your Meta account the same time as your main account even if you have no Meta activity whatsoever. However, this leaves the interesting question why this did not happen before for you – to which I have no answer.