... I’m Meg. In my free time, I enjoying crashing my friends’ cars, running over people’s feet, and not closing doors all the way before getting on the highway. Basically … don’t leave me alone with a car.
”Disappeared Dad: The father of the kittens is never seen or mentioned, although they express hope that O’Malley will take up the job (which he does). Given the different looks and ages of Berlioz and Toulouse, there was probably more than one father actually. That’s how it usually is with cats. Interesting to note: A sequel storybook was written sometime in the 80s. It obviously takes place after the movie as the geese sisters show up. But, O’Malley is completely absent from the story.
As Duchess is a pedigreed queen, it’s likely that Madame had her bred to an equally well-bred tom belonging to some other high-society Kind Hearted Cat Lover.
That still doesn’t account for the kittens’ different colors. In cats, black and orange fur are both dominant genes carried on the X chromosome, so a male can only carry (and pass on) one or the other. Marie’s easy to account for (white fur is a completely different gene, and recessive), but Berlioz and Toulouse have to have different fathers.” (Source)