15 year old Bobby come home from work early and catches his mother having sex with a stranger. His mother, Marie, finds out that Bobby saw her and tries to explain the circumstances but he isn't interested in her actions. Later when they are discussing her infidelity they fall into each other's arms and the sexual seduction of both mother and son begins.
A teenage boy whom lusts after his gorgeous, yet unattainable Mom, lives in constant frustration. At least until his Aunt comes to sleep on their couch after being released from psychiatric care. She's his Mother's identical twin sister, but unlike his real Mom, she's willing to explore his pent-up lusts.
A Story in the Ridiculous Universe
Many authors have suggested effects of a skewed sex ratio (e.g., Planet Grayson, Honor Harrington opus, David Weber; A Brother's Price, Wen Spencer). This story is nothing at all like those. Daymon's life is ordinary until he is called to meet a Visitor. Is the gorgeous naked girl a figment of imagination? Daymon's planet has a ~20:1 female:male ratio, uses a metric clock (metric-timeDOTcom), and has an orbital period 1/8 longer than Earth's (ponder what that means for individuals' ages).
Mom has a habit of getting herself off while she visits online chatrooms and looks at porn. She fantasizes about getting caught and fucked. It's all good fun until her son comes home early one day. Then it's great fun.
Tom Watson started out sexually servicing his mother and two sisters at age 14, and that was before he even had a girlfriend. By a quirk of circumstances, he and his girlfriend saved his middle school from an attack by some Muslim terrorists, and killed four of the terrorists in the process. Guess what: this got them thrown out of school. Eventually, those two and Tom's sister became vigilantes. Of course, for fun, there was a lot of sex.