Sue is named after Sue Storm, aka The Invisible Woman. She is neither invisible nor a woman, but when the kittens were born we thought she might be the only female in a group of four, immediately calling to mind The Fantastic Four. How can you tell Sue is female? Because she is a calico cat — a cat with white, orange, and black colouring. Black and orange cat colours are linked to the X gene, and since only females have two X genes, only female cats can have the two colours together.