Domestication Effect
Whether it’s a horse, a pig, a goat, lamb, or a domesticated duck, they almost all end up with white patches (piebaldism) or turning entirely white.
It’s called "Domestication Effect," and it’s one of the most fascinating "glitches" in biology.
When we select for "tameness," we are actually selecting for animals with reduced or slower-moving neural crest cells. Because the cells don't travel as far or as fast during development:
The real explanation - WHITE LIGHT does this. It can affect even trees (they don't have to turn white, but the fruits tend to be light in colour).