I would recommend a revision in the character definition. If players choose to go the incest route, changing from "brother" to "bro" and "sister" to "sis" once in a while would go a long way. As it is now, seeing "brother" and "sister" in the dialog regularly makes it a little cringy to read.
Ex: "Hey, sister. How's it going?" sounds cringy. However, something like, "Hey, sis. How's it going?" looks so much better.
Edit -
Aside from the aforementioned "bro vs brother" dialog, there's also quite a few glaring grammatical errors as well.
Ex:
That's just one example.