cat fun facts :D

One I like is that tortoiseshell/calico cats are hardly ever male due to
how the orange and non-orange pigment inheritance works! 
It goes something like this - on the x chromosome(s), there's a little switch
saying whether to be orange or not to be orange. Female kittens get two,
one from mom, and one from dad. If these are not the same (aka, if one
says "be orange!" and the other says "no, no!"), you get this beautiful
co-dominance effect from both options appearing on their fur, which is
tortoiseshell/calico. Male kittens inherit a y chromosome from their
dad, so they only ever end up with one x chromosome. The y chromosome is
a yes-man and doesn't fight what's on the x chromosome, so whatever is
on the x is what gets copied to the whole cat. That means you can't
achieve the co-dominance effect from two differing instructions arguing,
so you don't get torties.
Of course, there ARE exceptions for mutations, but these are very rare and, obviously, mutations!
I also remember hearing that the more white a calico cat has, the more
patchy the black and orange patches are. And, likewise, less white makes
the patches of differing color more brindled. I don't remember how that
works, exactly, but still cool!