HD Reptiles, Herpetology Defined
Reference

Ball Python Genetics Glossary

Definitions for the morph, inheritance, and breeding terms used throughout HD Reptiles and the ball python community.

A
Allele
One of two or more versions of a gene. Ball pythons inherit one allele from each parent at every gene locus, and the combination determines whether a trait is visual, het, or wild-type.
Axanthic
A recessive morph that reduces or eliminates yellow and brown pigment, producing a black, grey, and white animal. Multiple axanthic lines exist and are not compatible with each other.
B
BEL (Blue-Eyed Leucistic)
A solid white snake with blue eyes, produced by combining two copies of certain co-dominant genes such as Mojave, Lesser, or Butter. The specific pairing determines the clarity of the white and the shade of the eyes.
Breeding Project
A multi-year plan to combine specific genetic traits through intentional pairings. Projects track lineage, holdbacks, and outcomes across generations to reach defined genetic goals.
C
Clutch
A group of eggs laid by a single female in one reproductive event. Ball python clutches typically contain 4 to 8 eggs, though counts vary with the female's size and condition.
Co-dominant (Incomplete Dominant)
A gene that produces a visible effect with one copy and a different, usually more dramatic effect (the super form) with two copies. Pastel and Mojave are common co-dominant genes.
Clown
A recessive morph that produces a reduced, aberrant pattern with bold dorsal striping, intense color saturation, and a distinctive head pattern. Two copies of the clown gene are required for visual expression.
D
Dam
The female parent in a breeding pairing. Used alongside sire to document lineage and track genetic contributions across generations.
Desert Ghost
A co-dominant morph that produces a faded, high-contrast look with a distinctive super form. Desert Ghost combos are known for brightening and cleaning up pattern in multi-gene animals.
F
Fire
A co-dominant gene that slightly brightens color and reduces pattern. Two copies produce the Black-Eyed Leucistic (BEL), a solid white snake with dark eyes.
Firefly
A combination of Fire and Pastel, producing a brightly colored animal with reduced dark pigment. Firefly is a designer combo, not a single gene.
G
GHI
Short for Gotta Have It. A co-dominant gene that deepens dark pigment and increases contrast. The GHI super form is extremely dark with vivid pattern definition.
Gravid
A female carrying developing eggs, either fertilized or unfertilized. Gravid females typically show behavioral changes including reduced feeding and increased time on the warm side.
H
Het (Heterozygous)
Carrying one copy of a recessive gene without displaying it visually. A het clown animal looks normal but can pass the clown gene to 50 percent of its offspring when paired with another carrier.
Holdback
An animal retained by the breeder from a clutch for future breeding rather than being offered for sale. Holdbacks are selected based on structure, feeding response, growth, and genetic potential.
Homozygous
Carrying two identical copies of a gene at the same locus. For recessive morphs, homozygous means the trait is visually expressed. For co-dominant genes, homozygous produces the super form.
L
Leopard
A co-dominant morph that produces a busy, reduced pattern with speckling and increased contrast. The Leopard super form is a striking high-white animal.
Lineage
The documented ancestry of an animal, tracing its genetic history through recorded pairings across generations. Lineage documentation allows breeders to predict outcomes and avoid unintentional inbreeding.
M
Mojave
A co-dominant gene that produces a clean, high-contrast look with distinctive dark flames along the sides. Two copies of Mojave produce a Blue-Eyed Leucistic.
Morph
A genetic variation that changes the color, pattern, or both of a ball python. Morphs can be co-dominant, recessive, or polygenic and are the foundation of selective breeding projects.
N
Normal (Wild-type)
The standard appearance of a ball python without any known genetic mutations: brown and black patterning with a tan or gold base. A normal can still carry het recessive genes.
O
Ovulation
The release of eggs from the ovaries into the oviducts for fertilization. Ovulation in ball pythons is a visible mid-body swell and is one of the key markers breeders track during the breeding season.
P
Pairing
The act of introducing a male and female for breeding, or the specific combination of two animals selected for a breeding event. Pairings are planned based on genetic goals and project direction.
Paradox
A random patch of color or pattern that appears on a snake outside of its expected genetic expression, caused by a somatic mutation during development. Paradox markings are not heritable.
Pastel
One of the most common co-dominant genes. A single copy brightens yellows, reduces dark pigment, and produces green or hazel eyes. Two copies produce the super pastel, a dramatically lightened animal.
Phenotype
The observable physical appearance of an animal, as opposed to its genotype (the actual genetic makeup). Two animals can share a phenotype while carrying different hidden genetics.
Pos Het
Short for possible heterozygous. Indicates a statistical chance of carrying a recessive gene based on parental genetics, but unproven. A 66 percent pos het has a two-in-three chance of being a carrier.
R
Recessive
A gene that must be present in two copies (homozygous) for the trait to be visually expressed. Animals with one copy are het carriers. Clown, Axanthic, and Piebald are examples of recessive morphs.
S
Sire
The male parent in a breeding pairing. Used alongside dam to document lineage and genetic contributions across generations.
Spotnose
A co-dominant gene that produces a distinctive nose marking, increased contrast, and pattern disruption. The Spotnose super form is a dramatically altered animal with heavy aberration.
Super Form
The homozygous expression of a co-dominant gene, produced when an animal inherits two copies. Super forms often look dramatically different from the single-copy version and are sometimes given their own names.
V
Visual
An animal that displays a morph phenotypically. A visual clown shows the clown pattern, as opposed to a het clown that carries the gene without showing it.
W
Wookie
A co-dominant morph that produces a slightly altered pattern with a unique super form. Wookie is used in combination projects for its distinctive pattern-disrupting effects.
Y
Yellow Belly
A subtle co-dominant gene that produces a clean, slightly faded belly and minor pattern changes in single-copy form. Two copies produce the Ivory, a nearly solid cream or white super form.

Genetics Education

See It in Practice

Genetics HubBrowse Available Animals