Are male calico cats akin to unicorns? Oakland reader wants the real story

DR. JOAN: Next year, I intend to adopt a cat. I’ve always wanted a calico cat and will be on the lookout for one. I just think their coloring is so lovely and distinct.

My next-door neighbor informed me that if I get a calico, it will be a female. I wasn’t looking for a male or female cat, just a happy, beautiful cat, but now I’m wondering if all calico cats are female.

My friend said that if they ever found a male calico, they’d be wealthy because they’d be able to breed more male calicos. That didn’t sit right with me.

Can you tell me the truth?

— Natalie from Oakland

DR. NATALIE: Your friendly neighbor is partially correct, but since you asked, here’s the full story, as told by someone with a B+ in biology. I would have gotten an A if I hadn’t been too busy collecting insects for the class project.

Calico cats’ calico-ness is determined in part by their sex. Females, like humans, have two XX chromosomes, while males have one XY chromosome. A calico cat requires two Xs, one with black genetic coding and one with orange genetic coding. Genetics dictates that the cat will be orange and black if one X does not dominate the other. (I’ll come back to the white on the calico in a moment.)

Males lack the genetic instructions to produce the two colors because they do not typically have two Xs. Every now and then, however, a mutation results in a male cat with two Xs and a Y. The male could be a calico in that case. It’s uncommon, but it does happen. The genetic hiccup usually indicates that a male calico has other genetic mutations that can weaken him and shorten his life. However, there are cases where the boy is perfectly healthy and lives a normal life.

Calicos must inherit the white fur gene in addition to the black and orange genes. That gene can be found in both male and female cats.

If your friend finds a male calico, don’t expect to make a fortune by breeding a small army of the multi-colored cats. Calico males are born sterile.

Good luck in your search for your ideal calico. When you do, please send me a picture of her.

DR. JOAN: We successfully met our fundraising goal of $500,000 to protect and steward Krane Pond thanks to your assistance and the support of your incredible readers. We gratefully accept 257 donations totaling $61,361 from your readers.

Donations can be sent to Save Mount Diablo at 201 N. Civic Drive, Suite 190, Walnut Creek, CA 94596 or online at https://savemountdiablo.org/donate.

Save Mount Diablo, Ted Clement and Seth Adams

TO TED AND SETH: This is truly a season of giving and honoring all life, and I agree with you. There are so many wonderful organizations doing wonderful work that could use a little extra assistance now and throughout the year.