So yes, it's genetic. Marmalade Cats are Orange Blotch males.
The gene for orange blotch is closely connected with the gene for sex. The gene that codes for colour comes in a number of alternatives (alleles) these being for Orange, Orange Blotch or Beige(normal). The gene that codes for sex of course, codes for male or female (Mbuna don't have distinct sex chromosomes like mammals and birds, just a sex gene on an otherwise ordinary chromosome). Typically the female version of the sex gene is passed on with the OB version of the colour gene. But genetic recombination can lead to the sex gene for male being associated with the colour gene for OB. Result M Cat. It doesn't happen that often because the chances of the DNA fragmenting and recombining with the split being between two very closely associated genes is small. M cats are rare in the wild because they stand out from the crowd and so are more easy picked off by predators and those that do survive tend to be out-competed by normal males for mates. So although they would pass on a male sex gene with a OB colour gene if they did breed they often don't get the chance.
As yes inbreeding can increase the odds of getting M Cats. In captivity, M cats have a much greater prospect of breeding and so passing on their M cat genes. Inbreeding or breeding with OB females will increase the proportion of M Cat fry because the offspring will be getting the OB version of the colour gene from both parents and even with the chance of recombination in the next generation M Cat is less likely to be lost. So yes inbreeding can increase the chances of M Cats.
And hybridization. Again yes, because the OB gene associated with the male gene can be passed on as easily when breeding with a fish of a different species as when breeding with their own kind. For this reason I'd be suspicious of a M Cat of any species other than Labeotropheus, Metriaclima or Tropheops as I'm not aware of any other mbuna genera from which wild M Cats have been reported. And indeed suspicious of any species within those three groups in which M Cats haven't been recorded in wild fish.