Guys, question time.

I see so many comments about the stepsister thing that I'm really confused. The point of them not being blood related it's really easy to me, it's not a problem, they met already as big kids and the sisters relationship was not created even IF their parents tried to.

So is it some religious thing? Is it something constructed based on believes? Or a protest against SA, because we have innumerous cases of it happening inside homes? Or something else?

The argument about no just imagining doing it with your sibling (step or not) is really illogic to me because this seems like a fetishist approach, imagining putting yourself there, I don't know if you get me here.

Some step siblings can really have a genuine family relation, and we can see it happen naturally, even more when parents are there physically and emotionally to help build it, but like on this manga case, they could totally just got put together on their house and the parents saying "You are sisters now" but making nothing to help them to deal with another stranger living with them, so friendship was biuld first probably by them alone and evolved romantically later, and another point is if you discover that your lover is your sibling who you didn't know that exists, would you deal with it well because you didn't grown up together? Doesn't make sense to me.

I always had this inside my head since as kid when in mid 2000 I read a drama manga about really siblings falling in love (imouto bla bla, it's really trash) but I got really thoughtful when there got a point of the possibility of them not being really related.

So please, some opinions on this? I'm really curious about what's the mindset of your points.

PS. I don't even know why I'm asking this here