It is genetically impossible for the cat identified as Sylvester's mother to be his birth mother. A male cat's fur colour is determined exclusively by its mother's fur colour (it is transmitted on the X chromosome). The gene for red/orange fur (O) completely replaces black pigment, so a male cat with black fur cannot possibly have a mother with any variant of red/orange fur. The colour of the father's fur does not influence a male cat's fur colour.