Magical gene / no coat effect

Bird boned

Hollow-boned and light with it. Neither the horse nor its rider takes falling damage, from any height. The cheapest possible description of a gene that changes how you use the terrain.

Built, and not yet seen in game

The gene, its inheritance and its founder table exist and are covered by the test suite; the translator that turns it into behaviour was written against the 26.1.2 sources and is flagged unverified in its own comments. Nothing on this page has been watched happening to a horse. What to look at, and what is most likely to be wrong, is on To be verified.

What it does

Combination	Outcome
`Brd/Brd`	no fall damage, horse or rider, at any height
anything else	nothing

What it changes

Mountains stop having a wrong side. A ravine becomes a shortcut. It pairs obviously with magic jump, and the pairing is the point — jump is dangerous alone, and this makes the danger go away.

Health

Pure benefit, with one caveat worth knowing: it removes fall damage, not falling. A horse that falls into a ravine is unhurt and still in a ravine.

Gene key: horsegenetics.bird_boned
Alleles: Brd bird-boned, n
Inheritance: homozygous recessive
Reaches the game as: a traversal effect — fall_immune with target: both
Coat effect: none, ever

Immunity is a damage cancel, and it stores nothing

GeneAbilityHandler.onTraversalDamage cancels any LivingIncomingDamageEvent carrying the minecraft:is_fall damage-type tag when it lands on a horse expressing the gene, or on the player who is its first passenger at the moment of the hit. Nothing is written onto the player, so stepping off ends it and there is no immunity to carry away. The tick still resets the horse’s fall distance, which keeps the landing sound quiet.

Why not the per-tick reset on its own. Fall damage is applied inside the move, before the post-tick handler runs, so one tick at full speed still hurt. And a rider’s fall damage is the horse’s, passed down by AbstractHorse.propagateFallToPassengers, so resetting the rider’s own fall distance never protected them at all. Found 2026-09-10 while fixing fireproof, which had the same flaw and was caught in play.

Prefer the attribute to the reset, if either will do

safe_fall_distance is already in the attribute table and reconciles itself off. Where an effect can be expressed as an attribute rather than a per-tick reset, the attribute path gets removal for free — which matters more than usual here, because the grant reaches a player.

Nearly nothing to build

Of the three genes wanting rider-targeted traversal, this is the one with no other moving parts. If the shared target parameter is built against this gene first, the dangerous half of the change gets tested in the simplest possible setting before fireproof and ocean-born depend on it.

A gene whose value is entirely in another locus

On its own this is a safety net you rarely notice. Bred alongside magic jump, it turns a stat that mostly kills horses into one worth pushing. The mod has several of these — baiting beside health and fighting is the other clear one — and they are what make a stable a strategy rather than a collection.

Magic jump Fireproof Ocean-born What to check in-game

Planned source: common/genetics/genes/BirdBonedGene.java