One of my Sims has a small romantic relationship with her grandmother, and I didn't use cas.fulleditmode to edit relationships, just to change the last name of the grandmother long before the granddaughters came along. (The granddaughter is adopted -- not sure if that makes a difference.) Even more disturbing is that I downloaded a family from the Gallery to add some Sims to my game, and the granddaughter in question is romantically involved with one of the Sims, who has a Hot and Cold relationship with his daughter (they Dislike each other but have a mid-range romantic bar). I tried to use Modify Relationship cheat to get rid of the romantic bar and it wasn't working -- I may just have to invite her over and do Mean interactions to get rid of the romance bar (I did that with another Sim he had romantic bar with, and it got rid of the bar without hurting the friendship). Should probably take care of that before my Sim marries the dude. (He's got the Romantic trait so I'm not surprised to find a few entanglements.)
