I didn´t say that westerners don´t have inrahepatic Gallstones and that east asians (always) do have them.
I said that it´s (according to the professor) extremely unusual that westerners have them and that it´s a bit less extremely unusual that east asians have them.
If I remember it the right way, I´ve read that east asians get these intrahepathic stones mostly due to parasites that are more common in east asia then in the rest of the world.