Inheritance Types

The calculator handles five kinds of inheritance. Four of them give you concrete probabilities. The fifth — unknown — is honest about the limits of what the catalog knows.

Recessive

Two copies of the allele to express the morph. One copy is a het — a hidden carrier.

The classic case: Albino × Albino — every baby gets two copies, so 100% Albino. Het Albino × Het Albino is the textbook 1:2:1 — 25% visual, 50% het, 25% wild-type.

Here's where it gets honest: at hatch, a het and a wild-type baby look identical. The calculator collapses them into a single "possible het" outcome with the right percentage — see Het percentages for the rule.

| Sire ╲ Dam | Visual | Het | Normal | |---|---|---|---| | Visual | 100% Visual | 50% Visual + 50% Het | 100% Het | | Het | 50% Visual + 50% Het | 25% Visual + 75% "66% Het" | 100% "50% Het" | | Normal | 100% Het | 100% "50% Het" | 100% Normal |

Examples in the catalog: Albino, Piebald, Clown, Anery, Caramel, Tremper Albino.

Codominant (incomplete dominant)

One copy gives you the morph. Two copies give you a different, usually more extreme phenotype called the super form. Hets and homozygotes are both visible — they just look different.

The cross Visual × Visual gives 25% Super, 50% Visual, 25% Normal. The 25% that's homozygous becomes the super. Visual × Normal is 50/50.

| Sire ╲ Dam | Visual | Normal | |---|---|---| | Visual | 25% Super + 50% Visual + 25% Normal | 50% Visual + 50% Normal | | Normal | 50% Visual + 50% Normal | 100% Normal |

The super is its own outcome in the calculator and on saved hatchlings — it gets a "super" label, not just "visual."

When the trait is also flagged lethal-when-homozygous (Spider, Champagne, Hidden Gene Woma in Ball Pythons; Enigma in Leopard Geckos), the super is dropped from the outcomes and the rest re-totals to 100%. See Lethal flags.

Examples in the catalog: Pastel, Mojave, Lesser, Banana (sex-linked — see Sex-linked inheritance), Cinnamon, Yellowbelly, Hypo (in Boa).

Dominant

One copy gives you the morph. The homozygous form (two copies) looks the same as a single-copy heterozygote — there is no distinct super.

By convention, the calculator treats visual parents as heterozygous rather than homozygous. True homozygous dominants are rare in most lines, and assuming the homozygous form would over-predict visual offspring.

| Sire ╲ Dam | Visual | Normal | |---|---|---| | Visual | 75% Visual + 25% Normal | 50% Visual + 50% Normal | | Normal | 50% Visual + 50% Normal | 100% Normal |

Examples in the catalog: Spider, Champagne, Calico, Pinstripe, Enigma, Lemon Frost.

Polygenic

Multiple genes interacting, plus environmental and line-selection effects. There is no Punnett square that gives you "X% Tangerine" for a polygenic trait — outcomes vary by line, by individual, sometimes from one season to the next.

When the calculator hits a polygenic trait, it does not invent percentages. It returns a note: "results vary based on line selection." Honest is better than wrong.

Examples in the catalog: Tangerine (Leopard Gecko), Hypo (Bearded Dragon), Striped (Rosy Boa), most Bearded Dragon line traits.

Unknown

Some traits in the catalog have inheritance that hasn't been pinned down — either no breeding evidence, contested classification, or line-specific behaviour the keeper community has not agreed on.

When the calculator hits one of these traits, it returns a note: "cannot predict outcomes." The animal can still carry the trait — it just won't appear in offspring percentage predictions until someone characterises the inheritance. Examples include Strawberry, Black Night, Galaxy (Leopard Gecko), and Paradox traits in several species.

When the calculator can't predict

Two cases — polygenic and unknown — give qualitative notes rather than percentages. A multi-locus visual compound (Sunglow, Snow, RAPTOR, Blizzard) is also marked unknown for the same reason: predicting it as if it were a single gene would lie. See Multi-locus compounds.

This is intentional. The calculator is honest about the limits of what's known. If you want a number for a polygenic outcome, breeders' line history is the only source — not Mendel.