What??? Why would anyone play without the mod?? The incest aspect is what makes the game so hot!
Ehrmmmm...no!
Look, I don't mind a good incest game, but I like to play the developer's game, not some story cooked up by an incest fan.
In this game, you can clearly see that it was never intended to be an incest game. You are away with you Brother's Girlfriend on quarantine, her sister is also an established character. The tension between the brother and his GF is a MAJOR plot point, so I just don't see any way you can do incest in this game, without some major plot changes. There is also no Brother/Sister Mother/Son taboo tension between the 2 main characters. She pretty much likes him as a person from the start and flirts with him but is still loyal to her BF.
The tension between the 2 main characters is 100% due to their respective relationships to the MC's brother.
So no, I have no interest in playing an incest version of this game since it was clearly not written with that in mind.