Genetics Help - Could this be the Mother of my Chocolate Brown Cat?

[beckbjj]

My little chocolate brown cat Grace was rescued off a farm as an abandoned feral just under two years ago.  

Recently the rescuer found a white and black saddle mom cat in the same general vicinity, and she had a tiny chocolate brown kitten with her.  She of course rescued both mom and kitten, and kitten has been taken in by a neighbor and the rescuer has taken in the mom cat and has already had her vetted and spayed.  The vet said mom cat is about 10 years old.  

The rescuer says the brown kitten looked exactly like my Grace did when she was a kitten, and of course brown non-purebreed cats are pretty uncommon, so the theory is that this white and black saddle cat may be my Grace's mom (as well as the brown kitten's mom).

I'm generally pretty smart and good with science, but I admit that I have trouble getting my head around genetics sometimes.  My understanding is that to be chocolate, Grace would've had to get the recessive "b" gene from both parents.  But is it possible for a white and black saddle cat to carry that gene?  

Unfortunately I haven't got pictures yet of the mom cat or the brown kitten, but I have asked the rescuer to send me some and will post them if she does.  But her description was basically a mostly white cat with a black saddle.

The evidence of her actually having a brown kitten with her is pretty compelling, but if it's not genetically possible I guess that could mean she just kind of picked up this brown kitten somewhere along the line.

I would appreciate any thoughts on this!

 

[beckbjj]

Just giving this a quick bump, because I know for a while we had some folks on here who were pretty knowledgeable about  cat color genetics, and I'm hoping for help solving this mystery! :-)

 

[StefanZ]

 
My little chocolate brown cat Grace was rescued off a farm as an abandoned feral just under two years ago.  

Recently the rescuer found a white and black saddle mom cat in the same general vicinity, and she had a tiny chocolate brown kitten with her.  She of course rescued both mom and kitten, and kitten has been taken in by a neighbor and the rescuer has taken in the mom cat and has already had her vetted and spayed.  The vet said mom cat is about 10 years old.  

The rescuer says the brown kitten looked exactly like my Grace did when she was a kitten, and of course brown non-purebreed cats are pretty uncommon, so the theory is that this white and black saddle cat may be my Grace's mom (as well as the brown kitten's mom).

I'm generally pretty smart and good with science, but I admit that I have trouble getting my head around genetics sometimes.  My understanding is that to be chocolate, Grace would've had to get the recessive "b" gene from both parents.  But is it possible for a white and black saddle cat to carry that gene?  

Unfortunately I haven't got pictures yet of the mom cat or the brown kitten, but I have asked the rescuer to send me some and will post them if she does.  But her description was basically a mostly white cat with a black saddle.

The evidence of her actually having a brown kitten with her is pretty compelling, but if it's not genetically possible I guess that could mean she just kind of picked up this brown kitten somewhere along the line.

I would appreciate any thoughts on this!

I think you have solved the problem yourself.  If the  gene in question is recessive, its of course fully normal its not visible on the carrier.   Esp as white and black is a fairly strong gene.

I dont know nothing about this especial gene (that is why I havent looke at your post earlier), but I do know some about another recessive gene, the point gene.  Whom too pops up now and then.

Among a litter of otherwise looking cats, for example, purebred Russian Blue, now and then pops up an wonderful, look alike copy of siamese old type... This because, once upon a time 60 years ago, they did used a couple of blue pointed siameses in the breeding programme.  BUT, since 50 years, they dont use known pointed carriers russians in the breeding...

Its firstly now quite recently they had said OK to use known carriers for some breeding.   After all, being pointed is no sickedness.   Its more important to hunt for sickedness carriers than to witch hunt the point carriers, no?

So, if you are sure on your knowledge - that this is an recessive gene - here you do have your answer.

And thus,

If the father is another carrier with any looks, it will give typically one kitten of four being chocolade, one another carrier, two non carriers.

If the father is himself chocolade, two will be chocolade, two carriers with any looks.

As the mom is so old, its fully possible its SHE whom brought the gene into the colony.  The father and second  carrier in question being one of her descendants.

And thus, although you need two to dance tango, there is just one ancestor.   Paradox no?   No.