This is a disturbing fetish, but one of mine is of a young woman who wants to date and marry her mother, as well as vice versa, and get rid of her father. If the father is evil, this makes the fetish slightly less disturbing.
I saw other mothers and daughters who have very intimate love between them. Some like me, because they don't have a father, others because they do and don't get along with them, anyway, I'll speak for myself.
My mother and I have gotten along very well since I was little. As my father is absent, she raised me alone. As I grew older, I noticed that our taste in men was the same and we ended up meeting a man who we agreed to live with, together.
Unlike many people I talk to/talk to, my mother and I, when he is not present (or when we are in society), behave like a normal mother and daughter. When he is with us, and we are alone, both my mother and I are his lovers. the truth is, we are women, girlfriends, submissives... We are totally his and we love it.
But, as I mentioned above, we know how to differentiate our behavior in public places. We don't go around showing our intimacy and lust to everyone. We prefer to be confidential, and I believe that this helps us to have our privacy and also that 'forbidden' air.