The Latin phrase "In-Vitro" means "in an artificial environment outside the living organism." Thus, "In-Vitro" refers to the group of humans who were not only fertilized outside the womb, but had also gestated in a tank, to be "born" as young adults.

During the Alliance/Coalition War, the cost in human life was devastatingly high in the civilian population as well as in the military. Terror attacks claimed far too many. Combat and battle claimed even more. Everyday, the losses mounted. Humankind made the decision to increase its numbers artificially, not with the electronic intelligences that were now the enemy but with artificially gestated humans who could become highly skilled soldiers. Government and industry worked together to build a multitude of In-Vitro facilities around the country, facilities where these soldiers could be grown and trained.
After artificial fertilization, In-Vitros gestate in tanks, with umbilical cords at the base of their necks delivering the nutrients and basics they need as they remain suspended in a sleep state and under accelerated development. After about six years, their physical development is equivalent to a natural-born human at eighteen years of age. When they are "harvested" from the tank and awakened, they have the physical qualities of a fully grown human, but none of the intellectual or emotional attributes. They don't understand love of self, love of family, love of friends, or love of country. They don't understand the human world or anything about its society and how it evolved over the millennia. And nothing is done to remedy that deficiency. Instead of receiving any social education, they are indoctrinated into the art of killing.
Watched daily and trained by Monitors, they are never allowed to question anything. If they do, they are considered "defective" and promptly "erased." They are never released outside the facility until it is time for them to enter combat. Unfortunately, the production of In-Vitro soldiers was, "too little too late" as the saying goes. The Alliance was defeated and forced to flee into the uncharted reaches of space.

With the colonization of the Sirius sector, humankind found itself with a population of In-Vitros lacking purpose and reason. A social movement arose to incorporate In-Vitros into human society, to educate and develop them, to cultivate them for labor or possibly even other ventures. In response, there is a palpable backlash against it, as many feel that the In-Vitros (commonly referred to as "NippleNecks" or "Tanks", were to dangerous to the fledgling governments and were to be placed in cryo-stasis at an undisclosed facility. The last record of In-Vitro use was 80 years ago during the Sigma 13 battle of the failed Imperial Expansion War, after which they simply abandoned their ships and for all intents and purposes .... ceased to exist.

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This was written as a sort of back story to my character.
As well as a counter point to the CAF.