Eddie the cat has defied genetics and odds of 400,000 to one after he was born a MALE tortoiseshell.
Vet Karen Horne was stunned to discover the black and ginger tom, who overturns the normal laws of biology.
She said she named him after the cross-dressing comic Eddie Izzard because 'he is essentially a boy dressed in girls' clothing.'
Karen Horne with Eddie the cat. The rare kitten is black with ginger splotches
Male cats, like human beings, have only one X chromosome in their DNA meaning it is technically impossible for them to inherit different colours.
Of eight million pet cats in Britain only a couple a year are born male tortoiseshells - making Eddie an extremely rare accident.
Karen, 38, said: 'As a vet I can tell you that it is genetically impossible to get a male cat that is tortoiseshell coloured.
'My colleagues and I have 30 years of experience between us and we have never seen anything like this.'
The eight-week-old kitten was brought into Karen's veterinary surgery in Harpenden, Herts, with his three tortoiseshell sisters by local charity Cat and Kitten Rescue.
But as Karen set about vaccinating the siblings she discovered to her amazement that one was a boy.
It is almost impossible to get a male cat that is tortoiseshell coloured like Eddie
Karen, from nearby Markyate, was bowled over and immediately adopted Eddie into her family of five cats, four dogs and three children.
She said: 'I feel like the luckiest vet ever just to see a tortie tom cat, and even luckier to have him live with me.
'He a perfect cute little fluffy bundle. When he came in to the surgery, we all wanted to offer him a home.
'So far there are no signs of any gender confusion and he seems to be all there.
'In theory cats like Eddie should be infertile but he will be neutered when he comes to puberty anyway.'
Karen did not tell long-suffering husband Mike, 39, a lawyer, about the latest addition to the family, but he was soon won over.
Children Lucy, 11, Zoe, nine and Alex, six, and other cats Nia, Molly, Sterling, Harty and Herbie are equally delighted.
Viv Fowler, who runs the rescue centre that brought Eddie and his sisters in, said: 'In all my 13 years working for Cat and Kitten Rescue I have never seen a male tortie.'
