Odd-Eyed cats are the type of cats which has both eyes of the different color like one might be blue and other green or the combination of other eyes.
The reason is complete heterochromia. Heterochromia is difference coloration in hair and skin but mostly in the iris. It takes place due to lack of melanin caused by genetic mosaicism or injury or might be inherited.
This odd coloring is the results of either dominat white gene (epistatic) or white gene spotting preventing melanin particle to reach one eye before the development. It occurs when cats lack both white gene and this is rarely possible.
All the kittens are born with blue eyes and might change in early newborn age.