The relationship between the characters in Lewd Island is not defined.
It is up to you to pick what that relationship is and interpret it in your own way.
This is why we had to adjust certain dialogue lines so any of your possible choices could make sense and why certain lines just sound better than others.
The relationship between the characters was not intended to be incestuous, and we appreciate you pointing out potential misconceptions.
We will see what we can do about this.
Thank you!