An adult brother and sister (with flashbacks to their teen years) and his two teen daughters and their life together, swinging with neighbors, until they come to realize that they are more than just brother and sister. Note there is bisexual male/male sex and some watersports.
Alexandra's desires are awakened when she sees her father and his girlfriend fooling around in the hot tub one night. The girlfriend spots her and she runs away and waits for the inevitable telling off. But that isn't how it goes at all.
A Professor from a small town, makes it a game to rape teen girls. And all the girls cannot wait for their turn to be raped, including his own two daughters.
Cathy is a teenage cockteaser, a beautiful girl who delights in getting boys and men hot for her. But she is begining to lose control of her own urges, and even worst, she discovers she had been teasing her lonely dad for a long time.
Morgan has been invited to dinner to cement the sale of his business to Raygorn Designs. Having met his host's wife before Morgan is wary of the aggressive maneater. His 18 year old daughter Sally suggests she posed as his date for the evening to put the woman off. Somehow Sally takes the role more seriously than Morgan expected.
A story in the Karinaverse (Traveller) Universe
From the "Karinaverse"; now middle-aged (but well-preserved), Scout pilot Karina conceives twins by a young physics graduate-student passenger. Later, he unwittingly impregnates said daughters as well. (Contains futa-on-male and incest, so maybe not for everyone.)
Almost 40 years ago, our hero found a small Appalachian town where all the women had recently been blessed with bigger breasts and the men had become sterile. What did our hero do? Starts with minimal sex. That will change as as the story continues. (Tags include action in future updates)