This can be the plot of a game, or a comic, or any other work of pornography.
12 year old girl is made pregnant by her 13 year old bf who comes from an extravagantly wealthy and powerful family.
She gives birth to a girl, but due cheifly to the monstrous libido of the mother that made her intensely horny at all times, the couple never stopped boning, and next year she's pregnant again.
Again it's another girl, but the boyfriend really wanted a son to become the heir to his family fortune and to carry on the legacy of his family name and empire. So this process was repeated a total of 12 times before the mother finally got pregnant with a boy, and this news had the father overjoyed, but it just so happened that he died in an accident on the very morning of the exact same day as the birth of his son, which had occurred in the evening.
So the family of one mother and 12 older sisters welcomed their newborn son/baby brother on the same date as their husband/father had departed, the following year would be the very first occasion where the now 24 year old mother experienced having a period, since it was her first ovulation that had passed without pregnancy.
The boy is born with a special power that causes all females to be sexually attracted to and aroused by him. Despite him being as extremely average as can be in every other way (to the point of abnormal normality, extraordinary ordinariness, uncommon commonality, remarkable unremarkability, and unusual usuallness), all females are compelled to want sex with him, to physically pleasure him and to be physically pleasured by him, this is regardless of their relation to him, their ages, or even their species. This effect is especially potent upon his all-female family members, whose lust is heightened by the accumulative effect of their continued exposure to him.
So the plot is basically that you are a rich kid growing up from infancy in a mansion with your newly single mother and 12 older sisters, all of whom desire you sexually, as does all of the female staff of the house, and all the female animals your family keeps on site, and everything else out there with a vagoo.
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A second concept is about a prestigious family who bear a curse that removes the westermarck effect and causes them to lust after their relatives, the effect was effectively reversed, the more closely related and the more closely they were raised together, the greater the sexual desire for one another, sexual orientation is about the only thing that suppresses the attractions between family members. The curse also causes the children and adults to have the same sexual urges and psychology as pubescent teens, mraning that from the time they are born to the day they die, theyd be having a raging libido from what would gave otherwise been its peak intensity in their lifetimes.
The family had initially tried to avoid the intended effects of the curse by sending away all their children into adoption. But over time they came to accept the curse and even enjoy its effects. As had become customary each night, the fathers would sleep with their daughters, sons with their mothers, and brothers with their sisters, knowing the other was always interested in engaging in incest, and would never fail to welcome it, of course, the father and mother would also sleep together, but in this family the father and mother are very likely to be close relatives to one another.
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The coffin of Andy and Leyley seems to be the origin story of an inbred clan of satanic cannibals who hunt non-relatives, sacrifice their souls to hell in occult rituals, and then eat their victim's flesh while drinking their blood, they are incestuous, potentially they only exclusively procreate with their close relatives within the family. Wish there could be an alternative to chapter 2 where Andy rapes his mom and Leyley rapes her dad after the two siblings put on a show for their folks by fucking right in front of them, there could even be a long climax of a graves family orgy where the two male participants fuck each of the two female ones, and there could even be a lesbian pairing of Leyley raping her mom, then the siblings could sacrifice their parent's souls to Satan and consume the bodies left behind following the ritual.
