Real cat genetics in a browser game
Every cat in Catmaster carries a full genotype: pairs of alleles at loci, with dominant and recessive genes. Kittens inherit one allele from each parent, following Mendelian rules modeled on real cat breeding.
How inheritance works
Genotype with real loci
Cats carry gene pairs at loci such as brown, dilution, agouti, tabby or colorpoint – the set depends on the breed. Some alleles are dominant, others recessive, just like in real cats.
One allele from each parent
A kitten receives one allele of every gene from its mother and one from its father. Recessive traits can hide for generations behind a dominant allele – and suddenly reappear in a litter.
Sex-linked orange
The orange gene sits on the X chromosome. Tomcats carry only one copy, so they are either orange or not – so in Catmaster tortoiseshell kittens are always female.
Coat color inheritance – the Ragdoll example
Ragdoll colors are computed from the genotype, not picked from a list. A few examples of how genes combine:
| Color | Genotype behind it |
|---|---|
| seal | dominant BROWN allele, no dilution |
| blue | seal + two copies of the dilution gene |
| chocolate | two recessive brown alleles |
| lilac | chocolate + dilution |
| cinnamon | two copies of the rare brown1 allele (5% frequency) |
| fawn | cinnamon + dilution |
| orange / cream | X-linked orange gene (cream = diluted orange) |
| tortie (tortoiseshell) | female carrying one ORANGE and one orange allele |
Point intensity matters too: a cat with two siamese alleles shows stronger points than a heterozygous one.
Patterns differ per breed
Ragdoll
Body patterns: bicolour, highmitted, mitted and van, plus face and leg markings. Tabby stripes only show with at least one dominant AGOUTI allele.
American Shorthair
Four tabby patterns – classic, mackerel, spotted and ticked – plus silver and cameo shaded coats from the inhibitor and shaded genes, and 22 eye color variants.
Chartreux
True to the breed standard: only blue, from light ash to dark slate, controlled by a dedicated intensity gene.
Hidden traits and rare genes
Not everything is visible on the coat. Fertility and litter size can be checked at the vet – carried recessive genes stay hidden.
Fertility – 5 levels
From infertile (5% of newly generated cats; kittens inherit fertility from their parents) through low and average to good and high. Fertility decides the chance of successful conception – from 40% up to 95%.
Litter size (fecundity)
A separate hidden trait decides how many kittens a queen can have: from 1–2 up to 3–5 per litter.
Vet fertility test
A fertility test at the vet (150 Cat Coins, 7-day cooldown) reveals both hidden traits at once. Without it, a tomcat cannot be offered for stud.
Carriers and rare mutations
Rare mutations can appear at birth: each allele a kitten inherits has a small chance to mutate – vitiligo 0.5%, heterochromia 0.1%, blindness and albinism 0.01%. Mutated alleles are passed on; blindness is recessive and only shows when a kitten inherits it from both parents. Cats can also silently carry chocolate, cinnamon or dilution – you only find out when the trait shows up in a litter.
Pedigrees, certificates and champion titles
Every cat has a family tree: 3 generations of ancestors, or 4 after the level II Pedigree course. After completing the Pedigree courses in the Breeder Academy you can certify a full 3-generation pedigree with no repeated ancestors (500 CC) or a 4-generation one (1000 CC). Placings in the weekly Champions League earn champion points (when at least 3 breeders compete in the breed): 10 points make a Champion, and 30 points plus a 4-generation certificate make a Grand Champion.
FAQ
➜Is the genetics in Catmaster real?
Yes. The game models loci based on real cat genetics, with dominant and recessive alleles, X-linked orange, dilution and pattern genes. Kittens inherit one allele of each gene from each parent, so breeding outcomes follow real probability.
➜How do I find out a cat’s hidden traits?
Take the cat to the vet for a fertility test. It reveals both fertility and litter size.
Try real genetics yourself
Pair your first cats and watch the genes do their work. Free, in your browser.
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