[iCK]

Originally Posted by Sumeragi

Spoiler for Counterargument:

Major problem with that is it depends on Kirino not being a fully blood-related sister, but someone either adopted from outside the family or at least a cousin.

Spoiler for Countercounterargument:

Thats true, but it seems as though the parents don't care about kyosuke at all. Notice in the animes that they really only care about Kirino, they always ask where she has been and how her day was. Another thing I speculate is that Kyosuke might have been added via adoption or their taking care of him due to something unfortunate to his old family. before Kirino was born It also explains in kirino's true route that they aren't blood related siblings.Also in the anime, the mom of the house definitely knows something but isn't saying anything at all