Yabbut — Siamese?

Siamese cats are born pale all over and gradually acquire darker “point” colouring on ears, face, paws and tail. IIRC, this phenomenon arises from melanin cells that cluster in the cooler parts of the body.

I have two black cats, each of whom sports a little white patch on the lower belly that looks just like the visible part of a thong swimsuit. They’ve had those markings all their lives.