Some free sprited parents allow their kids to have sex with the parents and each other, leading to gang bangs and extremely perverted wet sex with others.
An 'In the Beginning' Story Part of the Tales of Olympus universe
After the Fall of Ouranos, Cronos is King on Olympus. While he sits on the throne, schemes and plots are still brewing and the hidden threat of a prophecy which foretells that one of Cronos' children will overthrow him.
After reading a pamplet on incest a brother and sister attend a meeting. In order for the brother and sister to join the Incest Club, they both must seduce a member of their own family. While the sister has her heart set on EVERY member of the family and the brother has his heart set on his mom and sister. With all the cummings and goings even the youngest teens see what is happening and join each other for a little tryst.
Dr. Alex Stone feels awkward talking to his son about the birds and the bees, so he gives the boy a picture book. When the boy's sister interrupts his reading, they learn a few things together.