trait-inheritance mechanic sourced
Trait inheritance
Offspring inherit traits or genes from their parents with recombination, variation, or mutation.
definition
Owns a genome per agent (gene list, trait set, or continuous parameters) and the reproduction operator that builds a child's genome from its parents: per-gene selection or crossover, optional dominance, and mutation with set rate and size. The genome then sets appearance, capabilities, or behavior parameters read by other systems. Creatures (1996) uses a haploid genome of about 320 genes coding receptors, reactions, and brain lobes, with crossover at gene boundaries, omissions, duplications, mutations, and genes that switch on at set ages. The Sims 2 passes appearance and personality with dominant and recessive genes; Crusader Kings III passes genetic traits; Planet Zoo genomes set lifespan, size, health, and fertility with an inbreeding penalty; Species: ALRE adds random values to numeric genes. Inputs: parent genomes, mutation parameters. Outputs: offspring traits and variation for selection or breeding.
player experience
Breeding becomes a long game of chance: the player pairs parents for desired traits, gambles on outcomes, and watches family resemblance and surprises appear. Lineages carry identity.
design levers
- genome representation (discrete traits, numeric genes, structural genes)
- inheritance rule (averaging, per-gene selection, dominance, linkage)
- mutation rate and size
- inbreeding penalties and diversity rewards
- visibility of genotype versus phenotype
failure modes
- Averaging inheritance regresses everything to the mean and removes surprise.
- Eugenic optimization: players breed for top traits and the system becomes a stat grind, with uncomfortable framing in human-character games.
- High mutation rates produce non-viable offspring that read as broken.
- Hidden genetics with no inspection make breeding feel random.
dynamics
- Selective breeding by the player concentrates traits across generations.
- With natural selection, inheritance lets populations adapt to environments.
- Inbreeding in small populations produces defect clusters that force outbreeding or trade for new stock.
open questions
- Can generative models map genomes to coherent novel appearances and behaviors rather than to a fixed set of parts?
- Which inheritance models keep breeding surprising without becoming a pure stat grind?