why wouldn't a beneficial mutation be passed down to descendants?

Question

Individuals are born with mana, which accounts for their life force and has a hand in determining the strength of their spells. Mana level and composition is determined by a person's genes, which they inherit from a mix of their parents. There are three factors that decide magical power:

1. Maximum reserve: This describes the level of reserves that a person contains. Individuals with extremely high mana reserves represent the strongest of witches, and can access the most powerful spells in mage craft. However, they have more difficulty in controlling and directing the flow of their mana. As a result, their spells take longer to perform. They also have a slow recharge rate, lengthening the time period between spells.

2. Focus rate: This describes the level of control a person has over their mana flow. Individuals high in this category have small reserves of mana, and can be considered weaker than average. However, they have much more control, allowing them to be more precise and direct. While those with high reserves are battering rams, they are a scalpel. They also have slow recharge rates, leading to longer intervals between spells.

3. Recharge rate: This is the category that most people fall into. They have average reserves of mana, as well as typical levels of control over it. They have a higher rate of recovery, allowing them to recharge their mana quicker than the other categories.

Very rarely, a person is born with high stats in all three sections. These individuals have large power levels with excellent control over their mana, as well as quick recharge rates. These individuals are considered the diamond in the rough, and are the most powerful and formidable mages in the world. The way evolution works, successful mutations are supposed to be inherited by descendants, as they allowed the parent organism to better survive and thrive compared to others of their race. As offspring becoming more successful, they eventually supplant others of their kind and become dominant. In the case of these badass mages however, their superiority only lasts once a generation. Their traits that make them powerful are not passed down to their offspring. Families who have instances of these mages often try pairing them in order to create a line of powerful offspring, but these are never successful in creating the desired outcome.

Why would this be the case?

Answer 1

These traits do pass on, but they aren't genotypes, they're phenotypes.

In our world we have a rather peculiar event regarding the fur color in some fox species: while in the summer their fur is usually "normal", once the winter arrives their fur color starts changing to white. This is due to the temperature influencing the genes which control pigmentation, with the sex of some reptiles being conditioned to this exact same environmental condition.

So here we can already see the issue: a phenotype (physical traits of an organism) isn't conditioned only to their genes, but to outside pressures that influence how these genes will manifest. Water fleas might be the best example of this: they have one of the most complex and long genomes in any animal. The reason? These genes help them adapt to various scenarios, growing structures such as helmets, spikes and other, as a way to better adapt to their environment and as a reaction to stress.

Your case could be experiencing a very similar scenario, in which the way these super mages grew was what allowed these traits to be expressed. Maybe it happened due to them living a much harsher life that wasn't shared by their preciously guarded and protected offspring, or by sheer stress related to the need of have more mana faster and control it triggering these changes in order to increase their chances of survival. This could easily result in a natural selection situation as well, in which a stressful and dangerous childhood is what allows these traits to appear. The stressful and dangerous conditions, however, will naturally limit the number of super mages due to the high mortality rate characteristic of such a harsh environment necessary to awaken the supermage genes. That way, if you don't help them they might die, but if you help them, they won't develop. It'll be a matter of one's cunning nature, luck and adaptability to be able to survive and live on, growing to be a force to be reckoned with, both due to their high power and to their great adaptability, fast thinking and cunning nature, which allowed them to survive in the first place.

Edit: to further decrease the number of successful Mages and the probability of achieving one, make the genes responsible for this condition recessive and more than one, preferably spread apart relatively from one another, this will ensure that simply having the necessary genes to be a supermage candidate will be extremely rare. The further apart these necessary genes are from one another, the harder it is to get all of their pairs, so it's a good way to further control the probability of a successful supermage being birthed and maturing under the necessary pressures, depending on how common or uncommon you want this condition to be. The genes responsible for the condition being recessive can also explain why normal parents could still give birth to a potential supermage child.

Answer 2

Similar to ProjectApex answer but different pressure: in parrotfish species, if there are no males In a school, one or two of the females will change gender. The presence of the male hormones from those couple males keeps the others as female.

Your badass mages are normal genotypes that are born at extreme nadirs of magic. Evolutionary pressure is against having too many badass mages in an area: that leads to conflict, which doesn’t help the species. When magic dips low enough, one or two badasses will develop. They have kids and bring the next generation up to “normal”, so there’s no dip.

You might have a rare case of badass spawning badass if the parent dies before the kid grows up and the kid grows up in an age of low magic. But that would require the parent have been a badass who didn’t use power much.

Answer 3

https://en.wikipedia.org/wiki/Heterosis

It is not some particular gene, but a combination of genes in a heterozigous combination for all of them.

Whoever you cross-breed the mage to, you get an average type of children with 99.9% probability. It is equally or even more probable to get the superior phenotype by just leaving people to procreate however they like.

To complexify the situation, each of these alleles is prevalent in some caste (race, whatever) and rare, but not unseen outside its home group. Using some "educated eugenics" you can improve chances by encouragin contacts between people of mixed race (but you will get mages of doubly-or-more-mixed race).

Answer 4

Genetics do not confer an absolute advantage or disadvantage. A gene (or combination thereof) may be advantageous in one environment and not at all in another. Even if the genetics of an individual are advantageous (at least in theory) there are many ways in which that advantage is not passed on to descendants. The individual may not mate and/or the off-spring may die from disease or disaster or war.

The key notion here is that evolution does not have a direction. More evolved does not translate into superiority, only to the notion that the entity is more suited to the current environment. Change that environment and the entities must evolve to fit that new environment or die. Even when the genetics and the environment line up, evolution merely says that the tendency is for the more suited entities to survive. Random events can easily disrupt this pattern.

Answer 5

Personality. There may be a minimum level of intelligence required to be an engineer, but intelligence only helps if you have a certain problem-solving mindset. If you don't have the passion for it, you have a lot of other options, but if you obsess over it constantly anyway, you can get good. I'm 6'4" tall, but was never good at football, because I have no interest in it. With a passion for football, I'd probably be quite good, but if I don't spend hours a day drilling the basics, that's not going to happen. Everyone thinks they want to be rich, but most rich people are that way because they obsess over money and finance. Presumably magic is a discipline, and a person's skill at any discipline is a combination of relevant genes and a personal obsession with the basics...possibly in multiple subdisciplines for a working above the card trick level.

Answer 6

The combination of genes that are required to produce very high magical ability is an extremely delicate balance. It's not just a gene that dictates the "ability score", but rather a complex intermingling of different genetic factors, and a change in even just one of these genes can undo the whole construction (for want of a better word).

Furthermore, the genes that dictate the three different abilities are at odds or in competition with one another somehow, which makes it all the more difficult to be good at all three.

So for someone who is good at all three abilities, if their offspring is missing just one of the many factors (which is likely because they will have inherited conflicting genes from the other parent) then the high powers will not be passed down.

Furthermore, these genetic factors are completely different in a woman than in a man, so even if two of these all-powerful mages get together, they won't necessarily produce an offspring with the same ability.