Genetics and inheritance
How genes make traits, what each parent can pass on, and where to explore the morphs you hope to hatch.
Contents
Genes and traits
A gene is part of what a gecko can pass to its hatchlings. A trait is something that gene makes visible. A gecko can carry a gene without showing it, so looks alone cannot tell you everything it might pass on.
Open a gecko in your Collection and choose its Genetics tab. The line there names genes that show, genes known to be carried, and strength traits. A question mark means a gene is possible, not confirmed.
See the Axanthic library sheet for one gene that can travel unseen, then follow how genes pass down.
Dominant and recessive traits
A dominant gene can show with one copy. A recessive gene, such as Axanthic, needs two copies to show; one copy can travel through a family unseen. With an incomplete dominant gene, one copy and two copies can make different looks. The two-copy look is sometimes called a super.
For a simple dominant example, a Black Base gecko with one B copy paired with a gecko without B gives each egg a 50% chance to inherit B and show black. With incomplete dominant Dalmatian, two one-copy parents give each egg a 25% chance of the two-copy Super Dalmatian look, a 50% chance of one copy, and a 25% chance of neither copy. These odds belong to each egg, not to a fixed number of hatchlings in a clutch.
Two copies are not always safe. For example, two Lilly Whites cannot be paired because a hatchling with two copies would not survive. That pairing would give each egg a 25% chance of the lethal two-copy form, so the game refuses it. Read the Lilly White library sheet for its appearance and caution. In Pairing, choose a female and then a male to read the preview. It shows possible two-copy forms and stops a pairing with a lethal or severe risk. Check that warning before planning a line. For a recessive example, follow how genes pass down.
Strength traits
Flame, Tiger and White Pattern pass down as percentages, rather than simple copy counts. The Genetics tab shows each strength. In the illustration below, Flame is 75%, Tiger is 50%, and White Pattern is 25%. These are example values, not a promise for a hatchling. The Flame library sheet shows how one of these patterns looks.
The game starts a hatchling near the average of the strengths its parents pass on. If one passes 25% Flame and the other passes 75%, their midpoint is (25% + 75%) ÷2 = 50%. The usual inherited spread around that midpoint is 10 percentage points. What the hatchling shows can vary by another 6 percentage points. These are spreads, not hard limits. A parent's visible strength may differ from the strength it passes on, so the pairing preview estimates from what you can see.
Open each parent's Genetics tab from your Collection, then compare them in Pairing. The preview gives a range for strength traits when both parents are chosen. Use the range as a possibility, not a guarantee. To see when a strength contributes to a visible label, read Morph names.
Base colour
Black, red and yellow are the starting colours beneath a gecko's patterns. Black can cover a red allele, so a black-looking gecko may still pass red to a hatchling. Yellow is part of the base too; the combination of inherited colours helps decide the shade you see.
On a gecko's Genetics tab, read the base entry before choosing parents in Pairing. If the red allele is confirmed under black, the line can show B/r. If it has not been confirmed, treat red as a possibility, not a promise.
For a B/r × r/r pairing, the black parent can pass B or r, while the red parent always passes r. Each egg has a 50% chance of B/r, visibly black while carrying red, and a 50% chance of r/r, visibly red. A parent with one yellow allele paired with one without it has a 50% chance to pass the yellow allele to each egg; yellow can change the visible base. Compare the Black Base, Red Base, and Yellow Base library sheets before choosing a colour goal. The inheritance examples show how to use a per-egg chance in a breeding plan.
How genes pass down
Each parent gives one copy of a gene to each hatchling. For a recessive gene such as Axanthic, one known carrier paired with a gecko without it has a 50% chance to pass on a carrier. None of that pairing's hatchlings would show Axanthic.
| Mother ↓ Father → | + | + |
|---|---|---|
| x | x/+ | x/+ |
| + | +/+ | +/+ |
When both parents are known carriers, each hatchling has a 25% chance to show Axanthic and a 50% chance to carry one copy. A visual Axanthic paired with a known carrier gives a 50% chance to show Axanthic and a 50% chance to carry it. Each egg has its own chance; a clutch is not required to follow those proportions.
| Mother ↓ Father → | x | + |
|---|---|---|
| x | x/x | x/+ |
| + | x/+ | +/+ |
| Mother ↓ Father → | x | + |
|---|---|---|
| x | x/x | x/+ |
| x | x/x | x/+ |
In each square, x/x shows Axanthic, x/+ carries it without showing it, and +/+ has no Axanthic copy.
Read the Axanthic library sheet to see the visual goal beside these odds. For colour combinations across the same parents, read Base colour.
To work toward a visual recessive, first keep or breed a known carrier, then find a second known carrier or a visual gecko. Open Pairing, choose the female and a candidate male, and read the gene-by-gene odds before you commit. A possible carrier is less certain than a known carrier, so its outlook can change as you learn more.
Morph names
A morph name describes the visible mix of base colour, patterns and other expressed traits. It can change when genes combine. The name does not list every hidden gene a gecko carries.
Open a gecko in your Collection and compare its name with its Genetics tab. Use the genotype line for what is known about inheritance; use the name for the look. If you want to see how a named morph appears across combinations, open the Flame library sheet. The strength traits section explains why the visible percentage and inherited strength can differ.
The Morph Explorer
The Morph Explorer keeps a record of the morphs you have encountered. Not yet means you have not kept one that shows it. Kept means one has been in your collection, and Bred means you hatched one yourself. A carrier alone does not fill a visual morph entry.
Open your Morph Explorer from the sidebar. Choose All, Kept, Bred or Not yet to narrow the grid, then open an entry to see the morph and its discovery state. If you want to work toward a missing entry, inspect its gene in the Axanthic library sheet and compare parents in Pairing. Follow how genes pass down to plan a recessive discovery.
The Morph Library
The Morph Library is a public reference for the looks Gecktopia can draw. Its entries show the morph on a gecko, explain where it appears, and show how it changes with other genes. Library art is an example of a look, not a prediction for a particular egg.
Open the Morph Library and choose a morph from the contents. Read its examples before choosing a breeding goal, then use Pairing to see what your own parents could produce. The Library explains the look; the pairing preview gives the odds for your selected geckos. Start with the Axanthic sheet to compare an illustrated look with the inheritance odds.