Sian is such a blue eyed beauty.

[Nac Mac Feegle]

15. I seem to remember something about a cat's eye color

That if they have enough fat in their diet, they will have a better chance of having green eyes when they get their final color. It was discussed about black cats, specifically.

So they are yellow or gold eyes as a default, but with sufficient dietary fats, they end up being green.

So a green eyed black cat is a sign of very healthy early childhood nutrition.

I can’t find the original article, so I may be mis-remembering. If someone can either confirm, disprove, or expand on this, please go right ahead.