Mewgenics Breeding Basics: Dominant vs Recessive

Mewgenics is, at its heart, a genetics simulator dressed in fur. Every cat you breed carries a pair of alleles for each trait — one from each parent — and the rules governing which traits express follow classic Mendelian genetics. Understanding this is the single most important skill in the game; everything else, from combat strategy to spell stacking, sits downstream of it.

Alleles and Genotypes

Each trait exists on a scale of two alleles: a dominant form (written as a capital letter, e.g. A) and a recessive form (written lowercase, e.g. a). A cat’s genotype for any given trait is the pair of alleles it carries, which can be one of three combinations:

A dominant trait expresses whenever at least one dominant allele is present — that means both AA and Aa cats look the same on the surface. The recessive trait only expresses when a cat inherits two copies (aa). This is the source of the most important concept for Mewgenics breeders: carriers.

How Inheritance Works

When two cats breed, each parent passes one allele to the offspring at random. If Parent 1 is Aa and Parent 2 is Aa, you get a 25/50/25 split:

• 25% chance of AA (dominant, pure)
• 50% chance of Aa (dominant, carrier)
• 25% chance of aa (recessive expressed)

This means even two cats that look identical (both expressing the dominant trait) can produce a cat with the recessive trait — if both are carriers. Conversely, breeding two aa cats together guarantees all offspring express the recessive trait.

Concrete Examples

The game ships with several traits that illustrate the system cleanly:

• Strong grants +3 STR and is dominant. One copy is enough — an Aa cat is just as Strong as an AA cat in combat.
• Weak inflicts −2 STR and is recessive. Your cat won’t suffer it unless both alleles are aa. An Aa cat looks fine but passes the hidden allele to roughly half its offspring.
• Lucky grants +3 LCK and is recessive. Getting two Lucky cats to breed and lock in the aa genotype takes intentional effort, but the payoff is permanent and stackable across generations.

These aren’t edge cases — they’re the template for how dozens of other traits behave. Many highly desirable traits in Mewgenics are recessive, which is what makes planned breeding necessary rather than optional.

Reading Inheritance Odds at a Glance

Before you pair two cats, it helps to think in terms of what alleles each parent can pass:

• An AA parent can only pass A. Every offspring gets at least one dominant allele from this parent.
• An Aa parent passes A or a with equal probability.
• An aa parent can only pass a. Every offspring gets one recessive allele from this parent.

When you combine these: an aa × Aa cross produces 50% Aa carriers and 50% aa expressors. That’s a useful cross when you want to spread a recessive trait quickly.

Why This Matters Immediately

Even in your first run, you are making genetic decisions. The collar (class) you pick shapes which stats matter — a Fighter leans on STR, a Hunter on DEX, a Mage on INT — and the corresponding dominant/recessive trait landscape determines whether your early litters are competitive or wasted generations.

Start by cataloguing which cats are carrying recessive alleles for your target stat boosts. A cat that looks ordinary may be an Aa carrier for Lucky or some other high-value recessive. That hidden allele is the raw material your breeding program needs.

The most common beginner mistake is discarding cats that don’t express a desired trait. Carriers are sometimes more valuable than expressors: they let you introduce a recessive trait into a new bloodline without the penalty of a full aa cat in a role it can’t perform.

Next Step

Once you understand the basics of dominance, the logical next move is planning multi-generation crosses to reliably produce aa cats for recessive traits. Use the Trait Combinator to experiment with cross outcomes before committing your best cats.

Open the Trait Combinator →