>>54397593It's not, Gen 2's Japanese guide explained that. NoA didn't bother their arses explaining shit when they could instead brainwash children into buying toys instead.
The fact Game Freak saw fit to explain eggs in Gen 6 AGAIN only proves it. That the Japs had no issue with being told that, just like they didn't pitch an autistic monkey fit like /vp/ over shrinking, should tell you they long accepted it as Canon.