Miss Amanda Jones knows what she needs and how to get it. This story pushes the limits of physics, but isn't strictly science fiction. Temporarily suspend whatever you know about physics, and just accept the possibility.
It didn't take long after I first had sex with my dad my mom joined us. Imagine my surprise to find out she was an incest daughter as well! Her first experience had been a lot different so she wanted to be sure I things were better for me. Now that everything worked out it was time for me to learn what she had kept hidden from me all these years. I had never really given any thought as to how having sex with your mom would be different than being with your dad - beyond the obvious.