Sorry, that I'm late. They put in a trigger that activates a switch to change the dialogue. I tested out when I created my new game. On the first new game that I made I put in the default names and there was no incest dialogue. On the second new game, I changed Mary to Mom and it triggered the relationship switch which switched to the incest dialogue. That way they could bypass Patreon's policy because the player would have to explicitly change the name.