Classes are sorted into three categories: non-magic, neutral and magic. There are three classes per each category, and it used to be segregated by race. Up until the Necromancer Rebellion, a student's race would determine which classes they are eligible for. Races are divided into two categories -- non-magic and magic. All students, regardless of race, were eligible to enter one of the neutral classes: erasers, wardens, or couriers. Elves, fairies, demons, skygge, wizards and necromancers are considered magic races. Magic races were eligible to join the divines, alchemists or sorcerers along with the three neutral classes. Humans, dwarves, angels, drows and vampires are considered non-magic races. Non-magic races were eligible to join the vanguards, intermediaries or crusaders along with the neutral classes.
Today classes are not racially segregated. A non-magic character can be accepted into a magic class; however, class heads can have biases and ideas for their class that do not add up to the "acceptance rule," and it can be very difficult for a non-magic character to get into a magic class or vice versa.
Hybridizing two races will always have the same end result in their children. A child who is born of a magical and non-magic races, like an elf and a human, will always have no magic whatsoever. A hybrid between two non-magic races, like a drow and a dwarf, will always result in a non-magical child. When two different magical races hybridize, the resulting child may receive both parents' magic type but will often favor one type of magic over the other. The child may also only inherit one parent's magic type and have no trace of the other parent's magic: a common happening between a magically-inept couple. The magic inherited in that scenario is almost always from the mother, but in a few rare cases, the father's magic may be the one inherited (especially if the father has more magical potential than the mother).
Each magical race has a certain type of magic they excel at and some races have their own unique kind of magic. In a magic x magic scenario, a child from an elf and a skygge will have both shadow magic and natural magic, but likely favor one over the other. The mother's race and that race's magic will often be the one favored by the child since magic wears on the mitochondria.
Children who are of magical descent will either have genetics for or against them. Their magical endurance is determined through genetics and the most dramatic displays of power (or lack of power) as related to genetics come from full-blooded mages or from a child hybridized between two exceptionally-powerful mages.
A child's raw power is mainly dependent on the mother's raw power. If the father is a very powerful mage, it is possible some of his magical power will be found in the child, especially in hybrids. This "raw power" is simply the potential that the child has; reaching its full potential will require hard work and practice. Most of the children who have a lot of potential are not aware of their talent, especially hybridized children since they generally have to learn different ways to use magic. Genetics can work in as an antagonist as well.
Children with magically-inept mothers generally end up with next to no control over magic. If their father is a powerful mage, however, the child may turn out to have average power. A magically-inept child generally has random bursts of uncontrollable magical things happen around them. This is because their mitochondria can only hold a limited amount of magic and when the magic overloads, it comes out in strange ways and is most prominent in small children. Weak mages can prevent this from happening by doing a spell every day and the random bursts will become less frequent once the child enters adolescence.
There are a few documented cases where none of the above rules seem to apply to children. Very rarely, when a child comes from two magically-inept parents, the child can be extremely powerful. It is unknown as to why, but scientists speculate that the mothers of these children had a female ancestor with amazing magical potential and throughout the years, the mitochondria would become less able to channel this energy. Mainstream science speculates that there is a "recharge" period between powerful mages in a family in where mages will become less and less powerful until the mitochondria are "recharged." It is only speculation, especially since documented cases are so rare. The opposite can also happen.
A child can come from two extremely powerful parents and end up having little to no magical power. This is a more common happening and the chance of it appearing in a child is approximately 250% more probable in hybrid children. Scientists know more about this phenomenon since it is more common and the condition is known as Wayweizer's Disease. This disease is where the mitochondria are maxed in power from the parents and when they are passed to the child, they are nearly unable to channel magic due to nearly-constant use by the parents. Wayweizer's Disease is treatable, but very few people can afford the treatment. The treatment is a daily intake of musimite, which helps to overwork mitochondria. After five years of musimite intake, the mitochondria will be more conductive and the disease will be cured. Wayweizer's Disease may also go away on its own, but this usually does not happen until after middle-age and those mages who do outgrow it generally are unaware of their awakened power unless another mage informs them of the power they have.