© 2006 Paul Cooijmans
It has been observed genius is rare and discontinuous. Here are possible explanations for both phenomena:
Genius is so rare - about 1 in 5 to 10 million perhaps - because it requires a combination of features, some of which intercorrelate negatively. If two things intercorrelate negatively, it will be rare to find them both expressed strongly in one and the same individual. What exactly these features are is discussed elsewhere in more detail, but in short it is on the one hand intelligence and on the other hand disposition for various psychiatric disorders, which - the disposition, not the disorders - provide associative horizon and conscientiousness.
This negative correlation is found in the high range of intelligence, where it matters with regard to genius, as genius requires high intelligence. It is not claimed that the negative correlation holds over the full range of intelligence, and that is also irrelevant as geniuses are not found over the full range. This negative correlation in the high range of intelligence makes it very unlikely and therefore rare for someone to have extreme amounts of all three of the components of genius: intelligence, associative horizon and conscientiousness. It explains the rareness of genius.
Discontinuity of genius means that parents and children of geniuses are typically not geniuses. Talented yes, often, but not geniuses. Talent is inherited, genius is not. Genius "emerges", that is, may occur in relatively undistinguished families and to leave relatively undistinguished offspring. Talented yes, genius no.
This might be taken to suggest that at least some of the features required for genius are not strongly inherited, but acquired or developed during life. In other words, that some of the features have a significant environmental component. That they can be improved at will or through circumstances or events.
Probably these are located in the realm of conscientiousness, and probably it concerns only part of the traits that make up conscientiousness; most likely those that are not related to ethics. My article on conscientiousness gives a list of words describing it, and those not residing under "ethics" seem to be the best candidates for a larger environmental influence.
This does not mean that everyone can become a genius by improving his persistence, determination and so on (see the article on conscientiousness for all of the terms). One needs the other aspects too: intelligence, associative horizon, the ethical part of conscientiousness; in short, one needs talent too. But it explains why children of geniuses are mostly not geniuses; for while intelligence, associative horizon and the ethical part of conscientiousness are probably passed on genetically, the non-ethical parts of conscientiousness may have a smaller genetic component and depend more on aware decision, study, practice, circumstances and (dramatic) events in one's life, perhaps even education. They do not come for free with one's D.N.A., but one has to work hard and suffer for them, and that is where many talented persons are lacking; that is why almost all talented individuals are not geniuses.
Another reason for genius' discontinuity is its extreme rareness. If the configuration of traits needed for genius is as rare as suggested in the section "Rareness", and if some or most thereof are genetic, then in sexual reproduction such a configuration will inevitably be lost. Although a genius has greater chances of conceiving a genius child than has the average person, even a genius may have to produce several hundred, if not thousand, children to see one genius emerge among them. To reproduce genius, one needs to either clone it, retaining the precise genetic configuration, or use something like a sperm bank (including careful selection of females to be inseminated) to create vast numbers of children with multiple mates.
Both of these reasons may play a role in making genius discontinuous, although the latter may have more weight than the first.