Children of geniuses are stupid

There is the common belief that great people can't give birth to great children because nature always wants to make equilibrium that is why when nature gives everything to one person it is a little bit tired to give the power to his/her children.
And really, Newton and Kant were suffering from schizophrenia, Cesar and Napoleon were suffering from epilepsy, Pushkin and Goethe were inclined to manic-depressive psychosis.
There is even the theory that genius is the presence of the recessive gene of schizophrenia. This theory is not considered to be serious but it explains in a true way why children of great people are not so smart as their parents. And wanting to become the parent of genius think over whether you want to become the grandparent of schizophrenic.
There is also the theory according to which love is the only power that is able to give birth to genius. But in reality there are a lot of proofs that it is wrong opinion. Moreover it is also necessary to mention that there are philosophers that consider that great love results have no children in the end.
Investigations of American psychologists showed the connection of the intellectual development of the child with the structure of the family. There is the notion of the average intellect of the family. In the result of such theory the conclusion can be made that more children the family has less chances children have to develop their skills to the level of genius. Geniuses are usually unique and the youngest children.