Defaults to 200 (50 nuclear families: father+mother+boy+girl).
Nuclear families created until population target is reached.
Same seed → same sim (useful for comparing settings).
Disabled by default. Enables brother/sister pairings.
Pairing filter uses shared ancestors (searched up to depth 12).
Always on
Select one preference style (mutually exclusive).
One active
Vault-Tec reverse mode: biases pairing toward the closest legal relatives.
Strongly biases pairing toward the most distant legal matches.
No relatedness preference; pairing uses age fit and randomness only.
If unchecked, the sim relaxes constraints and/or accepts fewer births, and keeps running until extinction.
A target family size is drawn once per couple at marriage (truncated normal).
min / max / mean / σ
Used for ≥3rd cousins/unrelated unions.
3.00%
6.00%
3.30%
Default tuned toward severe first-degree consanguinity outcomes in closed populations (~38%).
38.00%
Applied to births flagged with defects; calibrated for severe congenital outcomes.
30%
Represents lasting reproductive impairment among severe defect survivors.
20%
Formula: p = 1 − (1 − r)^(1 + a·s), where r=union defect risk, s=consecutive inbreeding generations, a=0.75. Plain English: each additional consecutive inbred generation increases risk, but with diminishing returns rather than unlimited linear growth.
Compares defects/births over a recent window.
8%
Smoothing window for the “significant inbreeding” trigger.
Lightly lowers birth odds as population nears/exceeds this value.
500
Shifts the mortality curve younger/older.
72
Mechanics: Individuals age yearly; eligible singles form couples; couples attempt births during fertility years until their drawn family-size target is met.
Outputs Rule: ≥3rd cousins
Year
0
Initialization
Population alive
200
M 100 • F 100
Births / defects (window)
0 / 0
0.0%
Mean inbreeding (F) (window)
0.00%
Lower is better
Milestone: overall significant effects
Not reached
General population trigger from defect rate threshold.
Milestone: overall point of no return
Not reached
Sustained demographic death spiral trigger.
Milestone: inbreeding-attributable effects
Not reached
Triggers when inbreeding-exposed births show excess defect risk vs baseline.
Milestone: inbreeding point of no return
Not reached
Triggers when inbreeding burden materially drives irreversible decline.
Live log: marriages, births, deaths, rule relaxations, and collapse signals. Log is persistent.
People tables (sortable). Default sort is oldest generation first.
Alive
Gen
Name
Age
Spouse
Children
Parents
Health
Cause of death
Deceased
Gen
Name
Age
Spouse
Children
Parents
Health
Cause of death
Cousin detection: finds closest shared ancestor up to depth 12 to better model long-run closed-population kinship.