Pick what each parent carries and see every hatchling the pairing can produce, with the odds for each. Free, no signup, and it covers all 31 proven boa constrictor genes.
Boas carry more documented welfare problems than any other species here, and the one that catches people out isn't a trait at all — it's a combination of two harmless ones. The calculator predicts the litter and flags what's in it.
♂ Male
TRAITS CARRIED
Nothing selected — treated as a normal.
LEOPARD COMPLEX
MOTLEY COMPLEX
INCOMPLETE DOMINANT
RECESSIVE
DOMINANT
♀ Female
TRAITS CARRIED
Nothing selected — treated as a normal.
LEOPARD COMPLEX
MOTLEY COMPLEX
INCOMPLETE DOMINANT
RECESSIVE
DOMINANT
Predicted offspring
Add traits to one or both parents to see the odds.
Keep the pairing instead of re-typing it
My Reptile Atlas saves this against the two animals, then tracks the clutch through incubation and shows you how the real hatchlings compared to these odds. Free for up to 20 animals.
Hypo and Colombian Motley share a locus, and Morphpedia records the compound as fatal. Neither is dangerous on its own, which is exactly why the pairing is easy to walk into. The calculator shows that outcome in red with its share of the litter.
Six albino lines — Argentine, BWC, Kahl, Prodigy, Sharp and VPI — and four anerythristic lines. None of them are interchangeable. Pair two different lines and you get normal-looking double hets, not visual animals.
Super Motley is fatal. Super Aztec brings a wobble and infertility, Super Jungle brings fertility issues, and Super Key West and Roswell Laddertail both carry an unusually high death rate at birth. All are flagged where they turn up.
Leopard and Onyx share a locus and both carry documented digestion issues.
31 of the 36 traits Morphpedia lists have a known inheritance mode. The rest are line-bred and named below.
Hypo x Motley is a special case.These two share a locus, and Morphpedia records the compound as fatal. The calculator shows it in red with the share of the litter it would affect, because neither parent trait is a problem on its own and the risk is easy to miss.
The albino lines is a special case.Argentine, BWC, Kahl, Prodigy, Sharp and VPI albino are six separate genes that look alike. Pairing one line to another produces normal-looking double hets, not albinos — the same trap leopard geckos have.
The genes it covers
Every trait MorphMarket Morphpedia lists as recessive, incomplete dominant or dominant, grouped by how it inherits.
These share a locus, so an animal carries at most two of them and never all three.
HypoMotley (Colombian) · lethal super
LEOPARD COMPLEX — ONE LOCUS, 2 ALLELES
These share a locus, so an animal carries at most two of them and never all three.
LeopardOnyx
Traits no calculator can predict
MorphMarket Morphpedia classes these as polygenic or structural. They're real traits and they set prices, but they don't sit on a single gene, so no Punnett square predicts them. Anything quoting you a percentage for harlequin or flame is guessing.
Hypo (Salmon line)PastelSunglow line
What does work for these is records: pair the same two animals for a few seasons and your own hatch data tells you far more than any average could. That's what My Reptile Atlas is for.