diff --git a/gerbil-manager-web/src/genetics/__tests__/genetics.test.ts b/gerbil-manager-web/src/genetics/__tests__/genetics.test.ts
index eba549e..40a6608 100644
--- a/gerbil-manager-web/src/genetics/__tests__/genetics.test.ts
+++ b/gerbil-manager-web/src/genetics/__tests__/genetics.test.ts
@@ -273,6 +273,14 @@ describe('GEN-3a: Uw=G alias', () => {
     expect(fromDisplayString('AA CC DD EE UwUw PP spsp rere').G).toEqual(['G', 'G'])
     expect(fromDisplayString('AA CC DD EE uwuw PP spsp rere').G).toEqual(['g', 'g'])
   })
+
+  it('always RENDERS G, never Uw (breeder preference)', () => {
+    // Uw/uw is an input/import alias only; output must echo G/g.
+    expect(toDisplayString(fromDisplayString('AA CC DD EE Uwuw PP spsp rere'))).toBe(
+      'AA CC DD EE Gg PP spsp rere',
+    )
+    expect(toDisplayString(fromDisplayString('AA CC DD EE uwuw PP spsp rere'))).not.toContain('uw')
+  })
 })
 
 describe('GEN-3a: second spotting locus Sls (WP)', () => {