An unknown pink mist covered the earth for 7 days. After this "Pink Mist" incident, the human genetic code changed, receiving additional Z and z chromosomes. The X and Y chromosomes continue to carry the female and male characteristics, but while girls are born with the usual XX combination, the XY pairing for males has become impossible to accomplish with natural fertilization.
Males are now born with the XYz structure, with the "z" chromosome acting as a genetic parasite, stunting the Y chromosome and making all males shorter, effeminate and near infertile until their sexual awakening. After sexual awakening, men can become more masculine or remain effeminate depending on their choice.
A third gender has also fully emerged. Futanaris, or futas, have the XZ (larger Z) chromosomal structure. The Z chromosome acts as a genetic symbiote, giving futas fully functioning male and female characteristics. It also boosts physical capabilities of futas to Junior Olympic level strength with minimal training (the occasional jogging is enough).
Those with the Z or z chromosome are able to achieve bursts of superhuman level strength, stamina or even intellect during certain sexual activities.
FUTAGEN PILL- A pill made using the concentrated pre-cum of futanari in heat as a base ingredient. Used to alleviate the most common symptoms of sexual awakening and heat/estrus in all three genders. In some countries, the government mass produces Futagen for all it's citizen, while in others only the rich can pay for their children to take the Futagen pill daily.
All genders awaken at the age of 18 and constantly release sexual pheromones to attract a mate.
(FEMALE)
Women no longer have periods once awakened. Instead their body is in constant heat until being filled by viable sperm that contains the Z chromosome. Direct insemination in any orifice will alleviate the symptoms. Oral ingestion of Futagen during estrus can also alleviate the symptoms of heat. Upon vaginal insemination the female can choose to release her egg or not, removing the need for contraception. Women being fucked will test her partner's stamina. Men and futas that finish quickly are rejected.
Oftentimes women have to be fucked into submission more than once for her to release her eggs for insemination. Experienced women can fuck all day without a chance of insemination. Female pheromones are release via vaginal secretion and her. Female secretions can be used to force erections.
(BETA MALE)
After 18, men require their z chromosome to be offset by a larger dose of Z chromosome to become fertile and regain their male characteristics. Male pheromones are released via saliva and breath. Z chromosome ingestion can be done through the direct ingestion of futa sperm anally or orally. Oral ingestion of sperm or Futagen during heat reduce the pheromones being released drastically.
Anal insemination temporarily activates the Z and z genes together, placing men in a heat that needs to be released (ejaculate) or relieved (oral ingestion) immediately via sexual intercourse. The activation allows men in heat to experience a temporary but significant increase in strength, penis length and girth, and are able to overpower unprepared or unsuspecting futas.
(It is strongly recommended for an experienced female or the futa partner to receive the first insemination, as inexperienced males are usually unable to control their strength during heat and can leave female partners broken. Other males can also be used to alleviate the heat.)
A constant cycle of ejaculating immediately after being inseminated at least once a week results in greater muscle mass and height. A constant cycle of ingesting sperm orally after going into heat locks in the feminine traits. The former becomes ineffective while the latter remains permanent after 9 months.
(Different ratios and amount of cock sucking and ejaculating can mold their/your body into what you want.)
(FUTA)
Futas fall into a state of heat once awakened. Their cock is in a constant state of erection, and the girth and length increase a solid 50% during heat. During heat, pheromones are released through futa precum, which is constantly released and able to fill a cup within 3 minutes if excited. A gallon drum is often left between their feet during school or at home to collect the secretions. Futas sense of smell increase 10 times over as well, almost equivalent to a cat's nose, in order to better track their rivals' and potential mates' pheromones.
Futas seek mates with a vengeance, and once found, lose themselves in the rut. This process can take between a few minutes to days, depending on how backed up the futa is. Most futa girls in heat fuck the nearest available and attractive hole, regardless of gender.
(Futa) Baser Instincts:
A futa in rut without the benefit of Futagen will mark her territory with pre-cum. Two futas competing for territory will compete sexually, using the anus. A futa that that loses a territorial fight forfeits all rights to her body except her pussy for the day and has to remain within the winner's territory until the day ends. A futa that submits completely to another futa by the end of the day becomes a bitch, ripe for mating .
Due to their biology, futa bitches are unable to maintain an erection or get pregnant unless given permission by their Alpha. Alphas have the right to impregnate and/or discard their bitches at any time. This can occur within families as well, though it is rarer.
GENETIC PAIRINGSFuta (XZ) + Futa (XZ) = Futa (XZ), Female (XX), No child (ZZ)
Futa (XZ) + Female (XX) = Futa (XZ), Female (XX)
Male (XYz) + Female (XX) = Futa (XZ), Female (XX), Male (XYz) (only small z is carried over)
Male (XYz) + Futa (XZ) = Futa (XZ), Female (XX), No child (Zz), MIRACLE STUD (XYZ) (0.000001% chance)
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SCENARIOIn this universe, the treatment of futanari, beta male and women differ on a country to country or county to county basis. In some Asian countries that value men more, women could be seen as breeding cattle and futas are drained of their sperm to provide futagen for the men. In some villages in Africa, futas might be the hunter gatherer and men extinct, while in Germany, secret societies could be researching the perfect heat and breeding cycle to achieve the master race. In certain societies, to reflect the changes in gender and breeding, monogomy might have phased out with throuples being as or even more common than couples. It's up to you to decide.
INITIAL BRANCH TITLEName - Role - Country
Notes: The description tilted very heavily towards futas and betas. If you have any ideas for the female characteristics, pleases share. Also, feel free to write about the lesser known countries.