When a morph harms the animal.
Most reptile morphs are not on a welfare exclusion list. A small number carry recognised risks to the nervous system, body structure or skin, increase tumour risk, or can produce a lethal two-copy form. This page explains the relevant UK keeper and trade policies and why those traits are absent from the calculator.
What “banned” means here
REPTA’s deleterious gene policy says the listed morphs are prohibited for sale, breeding or acquisition by its members. The IHS’s 2020 notice names five morphs excluded from trade or sale at its events: Spider royal python, Enigma and Lemon Frost leopard geckos, Super Motley boa and Jaguar carpet python. The IHS subsequently says it has adopted REPTA policies, including the deleterious gene policy, for its shows. Responsible Reptile Keeping (RRK) republishes and explains REPTA’s register.
Scope matters. These are membership and event rules, and YoGecko’s own breeding exclusions. “Banned morph” on this page does not claim that keeping every listed animal is a UK-wide criminal offence. An animal already alive still deserves appropriate care. For the inheritance terms used here, see the plain-English genetics primer.
Royal python morphs
| Morph or combination | Risk type | Why excluded under REPTA’s policy |
|---|---|---|
| Spider | Neurological / vestibular | Inherited inner-ear abnormality associated with disorientation and a head wobble, sometimes severe. A visually “mild” individual does not remove the inherited risk. |
| Super Champagne | Lethal two-copy form | Fatal embryonic development or death shortly after hatching. |
| Super Black Pastel | Structural | High likelihood of an underdeveloped lower jaw and spinal or tail kinks. |
| Super Cinnamon | Structural | High likelihood of an underdeveloped lower jaw and spinal or tail kinks. |
| Super Hidden Gene Woma | Lethal two-copy form | Fatal embryonic development or death shortly after hatching. |
| Champagne × Hidden Gene Woma | Neurological combination | Severe neurological signs are often seen in this allelic combination. |
The named “super” entries are two-copy outcomes. That distinction matters when assessing a proposed pairing. Source: REPTA register.
Gecko morphs
| Morph or combination | Risk type | Why excluded under REPTA’s policy |
|---|---|---|
| Enigma leopard gecko | Neurological | Balance and coordination problems associated with Enigma syndrome. Also on the IHS 2020 event list. |
| Lemon Frost leopard gecko | Tumour | High risk of iridophoroma skin tumours. Also on the IHS 2020 event list. |
| Super Whiteout African fat-tailed gecko | Lethal two-copy form | Fatal embryonic development or death shortly after hatching. A one-copy Whiteout is a distinct state; pairings that can produce Super Whiteout require particular care. |
| Super Cappuccino crested gecko | Structural / skin | High likelihood of cranial, spinal, limb, nasal and dermatological abnormalities. |
| Super Lilly White crested gecko | Structural / skin | High likelihood of cranial, spinal, limb, nasal and dermatological abnormalities. |
Source: REPTA register; context from RRK.
Dragons, boas and others
| Morph or combination | Risk type | Why excluded under REPTA’s policy |
|---|---|---|
| Silkback bearded dragon | Skin / UV vulnerability | The two-copy form of Leatherback has fragile, flaking skin, poorer protection from UVB and greater risk of cuts, infection, burns and dehydration. |
| Super Motley boa | Metabolic | Loss of muscle tone and difficulty passing waste, with a severely shortened life. Also on the IHS 2020 event list. |
| Super Jungle boa | Metabolic | Poor digestion and muscle tone, fertility problems and a severely shortened life. |
| Jaguar carpet python | Neurological | Wobble and difficulty righting itself. Also on the IHS 2020 event list. |
| Skull Face western / plains hognose | Structural | High risk of skull and jaw abnormalities and malformation of scales, eyes or nose. |
Source: REPTA register.
Some risks arise from a combination.
REPTA separately advises against Spider × Champagne, Spider × Hidden Gene Woma, and the Super Spotnose royal python outcome because of neurological concerns. It lists Red Monster bearded dragon and Scoria boa under scrutiny, stating that evidence is currently insufficient to add them to its prohibited register. A watch item is not a settled diagnosis or a ban. The policy says its list is reviewed every six months; check the live register before planning a pairing. Read the current REPTA policy.
Why the calculator is narrower. It does not offer Spider, Enigma, Lemon Frost, Leatherback or Whiteout presets. Some one-copy forms can be viable, but a simplified calculator could casually propose a two-copy or allelic outcome with known welfare costs. Complex allelic relationships also need more than an independent-locus model. An omission does not imply every unlisted trait is safe.
Health before a novel appearance.
I will not deliberately breed or advertise animals with the high-risk traits listed here. If I offer an animal for sale, I will record its lineage, feeding, condition and care needs, and state any uncertainty about its genetics.
Keep the categories separate
Policy exclusion: REPTA member rule, IHS event rule or YoGecko choice.
Risk mechanism: neurological, structural, skin, tumour or lethal combination.
Uncertainty: a new claim belongs on a watch list until the evidence supports a stronger conclusion.
Reviewed 28 September 2026 against the linked IHS, REPTA and RRK pages.