Comment by Sigma_ on The Silent Daughter of a Duke and the Cold Emperor ~ The Child I Found in My Past Life Became the Emperor ~ - Chapter 17

@Sigma_ Because, while pregnant, Pie ate some foods from the Dark forest. When consumed, it increases the person's affinity with magic beasts. There's also the fact that magic beasts have green cores. As a result, Pie's child ended up having green skin since he has a higher affinity to magic beasts than most.

@Sigma_ did you read the chapter?

@Sigma_ did you even read the explanation in the story? It's almost like they explained it.