Asking Eric: Veterinarian sister lives with our parents, avoids her nieces. Where's the common ground?

Dear Eric: My younger sister and I are 18 months apart in age and used to be very close. Slowly over the years we have grown apart and somehow, we developed a strong undertow of animosity in our interactions. We now really only talk through our mother as a filter. I am trying to find a way to restart a friendly relationship and return to at least civil communication.