In the Game of Thomes S1E1 we see Ned and his party of Robb, Bran, Jon, Theon and Ser Rodrick to find a dead direwolf mother and her many little cubs and they they take the cubs, one for each of the Stark children. But we can see then and on various occasions when these pets are shown that they are all different looking. Ghost is completly white with red eyes; Greywind is mostly gray with slightly white underbelly; Lady and Nymeria are both nearly white with a slight gray shade near the ears; Summer is white with slight shades of yellow and gold; and finally Shaggydog is nearly completly black. So if all these cubs are born to the same mother how are they all so different. Does this happens in Canidae family animals or am I missing something? Thanks.