நாய் வாலை நிமிர்த்த முடியாது
Naai vaalai nimirththa mudiyaadhu
Meaning
However hard you try, a dog's curled tail won't stay straight - some ingrained natures simply cannot be changed by effort alone.
Story
A boy tied his pet dog's tail inside a pipe for days, convinced it would come out straight. The moment he removed the pipe, the tail curled right back. His father laughed and said, "some natures are simply beyond changing."
Reader's Note
Sometimes accepting - or simply keeping your distance - serves you better than trying to change someone who won't.