I'd forgotten that Wen was fake!Tibetan, because - yep, it's a Not-mentioned-on-the-Discworld thing, and I really can only tell whether someone's a HoC (Human of Color) because Colon's racist about them (Visit and Ping).

And then Lobsang has his own difficulties, because half of him is non-neurotypical, and guess which half becomes the 'dominant' personality when he's one person?

I'd argue that not having contact with one of his parents' culture doesn't make a person white, though.