I remember….

So I remember seeing this video about why Japanese men cheat. And I think it was on a tv show they explained the reason or it might just be the internet. So they said when their gf turns to wife and they have a kid, then sleeping with your wife is weird as it’s like sleeping with your family… and that’s y they cheat. But then I remember the insane amount of manga and stories in general by “male authors” where the sister is all over the brother. Like u want someone accessible and also set boundaries on that?!? Make it make sense!