diff --git a/lib/shared/ancestor-threads.js b/lib/shared/ancestor-threads.js
--- a/lib/shared/ancestor-threads.js
+++ b/lib/shared/ancestor-threads.js
@@ -3,6 +3,7 @@
 import * as React from 'react';
 
 import genesis from '../facts/genesis.js';
+import { useAllowOlmViaTunnelbrokerForDMs } from '../hooks/flag-hooks.js';
 import {
   ancestorThreadInfos,
   threadInfoSelector,
@@ -20,14 +21,23 @@
     state => threadInfoSelector(state)[genesis().id],
   );
 
+  const usingOlmViaTunnelbrokerForDMs = useAllowOlmViaTunnelbrokerForDMs();
+
   return React.useMemo(() => {
     if (!threadIsPending(threadInfo.id)) {
       return ancestorThreads.length > 1
         ? ancestorThreads.slice(0, -1)
         : ancestorThreads;
     }
-    return genesisThreadInfo ? [genesisThreadInfo] : [];
-  }, [ancestorThreads, genesisThreadInfo, threadInfo.id]);
+    return genesisThreadInfo && !usingOlmViaTunnelbrokerForDMs
+      ? [genesisThreadInfo]
+      : [];
+  }, [
+    ancestorThreads,
+    genesisThreadInfo,
+    threadInfo.id,
+    usingOlmViaTunnelbrokerForDMs,
+  ]);
 }
 
 export { useAncestorThreads };