Pets

It's a sex-linked thing. Tortoiseshell, blue-cream (aka dilute tortie), calico, and patched tabby or torbie are so often female that nobody ever thinks to check otherwise. Almost all male tricolors are infertile because the gene is sex-linked. There was once, before my brief time in the "fancy", a very famous tortie Persian male, Tortie Man of Dallas, who wasn't. He was in great demand for breeding, but he never sired another like himself. In fact, IIRC, he never sired another tortie male at all. I saw a picture of him once. He was a handsome boy. That was before Persians got as squish-faced as they are now.