According to the badges page, the requirements for Yearling are:
Active member for a year, earning at least 100 reputation
However, the bonus for associating SO-family accounts is 100 rep, as long as one of the accounts has at least 200 rep to begin with. I'm curious if that means someone could get the badge simply by being active on another SO-family site and logging in every few days.
For an example, look at me: I have SO, SF, SU and Meta accounts, all associated. I'm a frequent participant on SO, SU and Meta but have never posted on SF despite visiting every day. I certainly don't deserve Yearling.
So, to make this an actual question, could someone earn Yearling on a given site without really doing anything at all? Or, phrased differently, what is the definition of "active member"?
I know this may actually already be accounted for in the code, and therefore not a bug, but I couldn't find documentation and I was curious.