Good son: your grandma
From Create Your Own Story
"Well... you can´t do that!" he tells you.
"Incest is a sin, you know that! But it´s really weird. Your grandma was telling me something similar..."
"But god will forgive you since you are feeling bad about it and came to confess. As long as you don´t actually have sex with her and stop fantasizing about her you will be fine."
You step outside the booth again.
Afterwards your grandma and you drive back home.