Clearly in your world, red hair is a recessive trait and white hair is a dominant trait.
Well, in reality, red hair is a recessive trait, so that tracks. And goodness knows what colour the parents' hair might have been had it retained any pigment.
Monarchs in my game are usually born with white or gray hair, but somewhere on this character's mom's side, there actually was someone with red hair who unlawfully married into the family.
As far as the Christian samurai thing goes, that's a result of attempted colonization by the British, though because they didn't fully succeed, they just sort of picked up certain cultural traits of the other country.
The purple-haired Asian thing is literally just because it looks cool. His brother has silver hair, so.... XD
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