The amount of mana that a person will have throughout their entire life is determined at birth. Mana is the life energy that can be used by a person to produce spells. Certain spells require a high concentration of mana that exceeds the individual's amount, and would need to attain mana from alternate sources. This would force witches to cooperate to perform these high level spells, which come with its own difficulties. Extracting mana from others is a long and difficult process, as well as illegal. This energy becomes attuned to a person as they get older, making it almost impossible to steal it from them, even if constrained. There is however a simple solution to this.
Morgan Le Fay heads a powerful clan that has organized a crime syndicate. This crime family supplies mana to less scrupulous businesses and individuals through a scheme that involves a simplified process. Sperm and egg cells are "acquired" from various murdered mages and witches throughout the world. The fetuses are grown within artificial human constructs called Androids, which operate as artificial wombs. At this stage, mana is less attached to an individual, allowing for easy extraction. These biological androids incubate the human until its third trimester, at which point it terminates the fetus and harvest the life energy. The remains are disposed of through tubes while the extracted mana is stored within the android. When an order is placed, the mana is bottled into specially designed containers and sold on the black market.
This family has spread these baby farms internationally, with franchises in other parts of the world run by associate members of the syndicate. Each farm has the capacity to produce thousands of fetuses a year to be harvested for their energy and then sold, raking in millions of dollars. However, there is a curious problem having to do with quality that they have yet to solve. The average mage contains a mana level between 30 and 60. Combining the cells of mages with average power produces a child with around the same amount. Say one has a mana level of 30 and another has a level of 50, the resulting offspring will be somewhere in the middle. When combining the sex cells of high power mages ranging in the hundreds, the resulting offspring doesn't inherit that power boost. Instead, it is regulated to the average range.
One would naturally think that combining the cells of powerful mages would produce just as powerful offspring. Why would this not be the case?