Makes sense. My wife and her mom have very similar sexual tendencies, it's no surprise either since they were open about it around the house and my wife always knew what her mom was up to.
I think its important for us not to shy away from dark or unrealistic fantasies. Just like offensive comedy and horror movies, it's healthy for us to process and express our emotions and desires in a way that is safe but still exciting or interesting.
It's amazing how strong the mother-daughter connection can be as they grow up. I know my wife definately learned some kinks from her mom and it's just such a beautiful and sexy thing.