Rebecca Hardy, 27, was overjoyed when Mahri, her two-year-old Maine Coon, gave birth to a litter of seven in December.
But as the kittens each opened their eyes, she noticed that they all had convergent strabismus, where their pupils are turned inwards towards the nose.
As their extraocular muscles strengthened, six of the kittens adjusted their eyes to normal - but the seventh, named Red, did not.
"He's got a ridiculous amount of confidence for a cat that’s cross-eyed!"
She has been breeding the notoriously huge Main Coon cats with Mahri for just over a year, and Red, nicknamed 'Boz' after his boss-eyed expression, was in her second litter.
She and four-year-old son Eli spent three-and-a-half hours helping to deliver the seven babies at midday on December 18, and all appeared to be healthy.
The mum-of-one said: "They opened their eyes at about a week-and-a-half old and all the kittens were cross-eyed as the muscles have not strengthened enough.
"It's not very common but it's not dangerous, its very cute and we’d seen it in our other litter as well.
"It was only around week six or seven that we realised this little boy’s eyes weren’t going to straighten out, everyone else's had about the fourth week.
"He's a bit of an anomaly, he’s likely going to be cross-eyed for the rest of his life."
Despite his vision, Red had oodles of personality and grew to be the biggest of his litter, weighing 2.2kg at just 12 weeks old.