The smartest people, in general, have fewer children. In terms of the theory of natural selection and breeding rights, this implies the smart don't see themselves as the naturally selected, or else they would have the most offspring like in nature.
The instinct of the smart is not to depend on their genes, but on the money and means they have with respect to nurturing children. This high level of nurture will compensate for poor genes, with fewer children allowing the nurture to be more concentrated. The poor person has to depend on genes because cultural nurture is not at the same level of advantage.
In the olden days gone by, the royalty have more ways to nurture their children and therefore can compensate for less than premium genes. The poor did not have the same access to cultural nurture but had to depend on genes and instinctive nurture. The path of the poor appears to have selective advantage, which is why the poor are the dominant demographics. It would almost imply nature come first. While the royalty showed with enough nurture, the opposite can also work. However, this will not have selective advantage in nature, due to being too resource intensive, to be viable for all. Only a small group gets to use excess resource for an IQ boost that is free, if natural.
Stupid people, along with ugly people and Manchester United supporters should definitely not be allowed to have children. It's basic common sense.