diff --git a/simulation/SimNPC.gd b/simulation/SimNPC.gd
index 39aa8aa..4e770ff 100644
--- a/simulation/SimNPC.gd
+++ b/simulation/SimNPC.gd
@@ -32,6 +32,7 @@ var has_travel_target := false
 var inventory: Dictionary = {}
 var last_task: StringName
 var random_source: RandomNumberGenerator
+var familiarity: Dictionary = {}
 var debug_logs := true
 
 
diff --git a/simulation/SimulationManager.gd b/simulation/SimulationManager.gd
index 1416c7f..aa64c07 100644
--- a/simulation/SimulationManager.gd
+++ b/simulation/SimulationManager.gd
@@ -86,6 +86,12 @@ func generate_npcs() -> void:
 		for i in range(npcs.size()):
 			npcs[i].home_position = home_positions[i % home_count]
 
+	for i in range(npcs.size()):
+		for j in range(i + 1, npcs.size()):
+			if npcs[i].home_position.distance_to(npcs[j].home_position) < 4.0:
+				npcs[i].familiarity[npcs[j].id] = 0.5
+				npcs[j].familiarity[npcs[i].id] = 0.5
+
 
 func _create_random_source(npc_id: int, stream_id: int) -> RandomNumberGenerator:
 	var source := RandomNumberGenerator.new()
diff --git a/simulation/state/NPCStateRecord.gd b/simulation/state/NPCStateRecord.gd
index e19c44c..e4ed081 100644
--- a/simulation/state/NPCStateRecord.gd
+++ b/simulation/state/NPCStateRecord.gd
@@ -45,7 +45,8 @@ static func capture(npc: SimNPC) -> NPCStateRecord:
 			"inventory": npc.inventory.duplicate(true),
 			"last_task": String(npc.last_task),
 			"random_seed": str(npc.random_source.seed),
-			"random_state": str(npc.random_source.state)
+			"random_state": str(npc.random_source.state),
+			"familiarity": npc.familiarity.duplicate(true)
 		}
 	)
 
@@ -160,6 +161,9 @@ func restore(debug_logs: bool) -> SimNPC:
 	npc.last_task = StringName(data["last_task"])
 	npc.random_source.state = String(data["random_state"]).to_int()
 	npc.debug_logs = debug_logs
+	var saved_familiarity = data.get("familiarity", {})
+	if saved_familiarity is Dictionary:
+		npc.familiarity = saved_familiarity.duplicate(true)
 	return npc
 
 
diff --git a/tests/npc_schedule_test.gd b/tests/npc_schedule_test.gd
index 9a9d271..1ab8f80 100644
--- a/tests/npc_schedule_test.gd
+++ b/tests/npc_schedule_test.gd
@@ -14,6 +14,7 @@ func _run() -> void:
 	_test_sleep_restores_energy()
 	_test_schedule_serialization()
 	_test_sleep_targets_home()
+	_test_household_familiarity()
 
 	if failures.is_empty():
 		print("[TEST] NPC schedule passed")
@@ -181,6 +182,63 @@ func _test_sleep_targets_home() -> void:
 	manager.free()
 
 
+func _test_household_familiarity() -> void:
+	var manager: Node = load("res://simulation/SimulationManager.gd").new()
+	manager.simulation_seed = 700
+	manager.debug_logs = false
+	manager.set_process(false)
+	manager.home_positions = [
+		Vector3(-15.0, 2.0, 7.0),
+		Vector3(-15.0, 2.0, 8.0),
+		Vector3(-8.5, 2.0, 3.0),
+		Vector3(-6.5, 2.0, 1.5),
+		Vector3(20.0, 0.0, 20.0),
+		Vector3(22.0, 0.0, 22.0)
+	]
+	root.add_child(manager)
+
+	var a: SimNPC = manager.npcs[0]
+	var b: SimNPC = manager.npcs[1]
+	var c: SimNPC = manager.npcs[2]
+	var d: SimNPC = manager.npcs[3]
+	var e: SimNPC = manager.npcs[4]
+
+	_check(
+		a.familiarity.has(b.id) and b.familiarity.has(a.id),
+		"NPCs with nearby homes should be mutual household members"
+	)
+	_check(
+		is_equal_approx(float(a.familiarity[b.id]), 0.5),
+		"Household familiarity should start at baseline 0.5"
+	)
+	_check(
+		c.familiarity.has(d.id) and d.familiarity.has(c.id),
+		"Second household pair should also be familiar"
+	)
+	_check(
+		not a.familiarity.has(e.id),
+		"Distant NPCs should not have household familiarity"
+	)
+
+	var saved_json: String = manager.serialize_state()
+	var restored: Node = load("res://simulation/SimulationManager.gd").new()
+	restored.debug_logs = false
+	root.add_child(restored)
+	restored.set_process(false)
+	_check(
+		restored.restore_state_from_json(saved_json),
+		"Familiarity should survive save/load round-trip"
+	)
+	var ra: SimNPC = restored.npcs[0]
+	_check(
+		ra.familiarity.size() > 0,
+		"Restored NPC should retain household familiarity"
+	)
+
+	manager.free()
+	restored.free()
+
+
 func _check(condition: bool, message: String) -> void:
 	if not condition:
 		failures.append(message)