@nyamcam nah, son-in-law looked completely different, and I wasn't really paying attention, so don't take my words for it, but I think the story doesn't match up. Also he said Father not Father-in-law.
@Bean_Soup It's probably because the kid resembles his uncle? And I think it's more about how one would perceive a stranger differently than their family members, despite if there is family tension or not. He portrays himself and his family as childish drawings, and I think it is to differentiate relationships. Like, because he knew the appearance of his family members, he isn't able to recognize each individual trait of their face and bodies, only that "this is Mama Punpun, Papa Punpun, etc." Like how kids don't usually know the names of their parents nor family outside of last name or nicknames. That's just a theory though.