8-week-old kittens not using litterbox?

A friend of the family has a cat who got pregnant by her brother . The resulting 4 kittens are now 8 weeks old, and evidently have no litterbox manners. I have never seen the kittens, so I'm only going on what she told my mom over the phone. She says the litterbox is shallow enough, clean enough, and the kittens go potty right next to it. So it's not a matter of the litterbox being too far away. She tried to confine them to the bathroom, but the mother cat couldn't handle being confined OR being away from her kittens. She feels it's because they're retarded due to being inbred. She wants to take them to the shelter (kittens are usually adopted quickly), but of course if they don't have litterbox skills, their future doesn't look good.

Any ideas? I could[/] take them to my house, but I already have a feral mama and her 4 kittens, plus 2 kittens from an orphan litter. So if I took them to my house, there would be 10 kittens in the spare bathroom. Which is maybe a bit excessive, LOL.

Note: the mama cat will be spayed....I already contacted the low-cost clinic. Plus she's being kept indoors, without her brother being allowed to visit

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I think it takes more than one inbreeding to cause retardation in cats. Most likely their mess gets cleaned up, so they don't really feel a need to bury it. I've had the best result litter training by putting it in the box rather than disposing of it. They smell it there, and you can almost see the little light bilb over their heads when they get it. It could be that they are playing or sleeping in the box and won't soil it.

That is a good suggestion... put the poop or a piece of kleenex soaked with pee in the box so they get the idea. Also - make sure any area where they eliminated is cleaned with an enzyme cleaner to get rid of the telltale scent so it doesn't smell tothe kittens like someplace to potty.

Anothe suggestion ... Dr. Elsey's kitten attract litter or additive. People on here have used it and say it works like a charm. If you cannot find it at a big box retail pet store, perhaps you can get it online. It is expensive, but you don't need to fill the litter box with it.. add a layer on top.