FAQ

Lethal Flags

Some morphs are lethal in the homozygous form. The animal never hatches — the embryo dies in the egg. The single-copy heterozygote is fine; the double-copy super is not.

Four traits in the catalog carry the lethal flag today:

  • Spider (Ball Python, dominant)
  • Champagne (Ball Python, dominant)
  • Hidden Gene Woma (Ball Python, codominant)
  • Enigma (Leopard Gecko, dominant)

These are the well-documented cases where the super has never hatched, or has only hatched as severely deformed and non-viable. The catalog reflects breeder consensus, not edge-case anecdotes.

What the calculator does

When two parents both express a lethal-flagged trait, the textbook 1:2:1 gives 25% homozygous offspring. Showing that as a "25% Super Spider" outcome would be misleading — those eggs never hatch. The calculator does two things:

  1. Drops the homozygous outcome — the non-viable genotype is removed entirely.
  2. Re-totals the remaining outcomes so they add up to 100%.

The user-facing note reads roughly: "25% Super Spider — non-viable; remaining outcomes re-totalled." You see the math and the reason in the same place.

Worked example: Spider × Spider

Spider is dominant. Without the lethal flag, a Spider × Spider cross gives:

  • 25% homozygous Super Spider
  • 50% visual Spider
  • 25% normal

With the lethal flag, the 25% Super is dropped. The remaining 75% re-totals:

  • 50/75 = 66.6% visual Spider
  • 25/75 = 33.3% normal

That's what the calculator returns: 67% Spider, 33% normal (the 67/33 numbers are rounded for display).

Worked example: Champagne × Champagne

Same shape as Spider — Champagne is dominant. Visual × Visual gives 67% visual Champagne / 33% normal after dropping the lethal super.

Worked example: Hidden Gene Woma × Hidden Gene Woma

HGW is codominant, so without the lethal flag the cross is 25% Super HGW / 50% visual HGW / 25% normal. Dropping the super gives:

  • 50/75 = 66.6% visual HGW
  • 25/75 = 33.3% normal

Same re-totalled distribution as the dominant cases — the lethal handling doesn't care whether the underlying inheritance is dominant or codominant; either way the homozygous form is what dies.

Lethal vs welfare — they're independent

The lethal flag and the welfare flag are two separate things on a trait:

  • Lethal-when-homozygous is about the super form (two copies). The calculator drops it from the outcomes. Affects the math.
  • Welfare concern is about the heterozygote that you actually keep — Spider's wobble, Hidden Gene Woma's mild wobble, Lemon Frost's iridophoroma risk. The calculator does not change anything based on it; it surfaces on the public profile as a buyer-facing card.

A trait can carry both flags, either, or neither:

| Trait | Lethal super? | Welfare? | |---|---|---| | Spider (BP) | Yes | Yes — wobble | | Champagne (BP) | Yes | Yes — mild wobble in some | | Hidden Gene Woma (BP) | Yes | Yes — mild wobble in some | | Enigma (LG) | Yes | Yes — Enigma Syndrome | | Lemon Frost (LG) | No | Yes — iridophoroma | | Pinstripe (BP) | No | No | | Pastel (BP) | No | No |

The Lemon Frost case is the sharpest illustration of why the flags are independent. The super form is viable — homozygous Lemon Frosts hatch — but the trait carries a documented welfare concern (skin tumour risk) that gets worse in the super and shortens lifespan. Dropping the super would be wrong; informing the buyer is right.

For the full table of welfare-flagged traits with their plain-English warnings, see Welfare flags.

Why we don't flag "deformed" or "small clutches"

Some breeders argue that other morphs (Caramel, certain BluEL combos) produce lower hatch rates or higher deformity rates. Those claims exist but aren't consistent enough across breeders to bake into the calculator. The catalog's lethal flag is reserved for cases where the super is reliably non-viable — not "smaller clutch" or "occasional kink."

If you have evidence a trait belongs in the lethal list and isn't there, that's a curator decision: open the catalog and add the flag with a curator note pointing at the evidence.