Else you may be in for a very long payback period.
Scientists have determined that wild crows have a grudge gene --- something that allows the crow to remember individual people & harass them for years. Ok. So maybe I went overboard with the grudge gene terminology but these birds take payback to the extreme.
I bet my mother-in-law is linked in the evolutionary chain to crows somehow ...
Here's the NPR article. Make sure to listen to the audio.