4. Genes. Although smart couples tend to have fewer, not more, children (which might lead us to expect intelligence in the population to drop over time), it's possible that due to better education, tracking , and testing, those who do have the right genes are better able to exploit those advantages. Some genetics researchers also have argued that if genes for intelligence carried by both parents are dominant, they win out, meaning the child's IQ will be as high as or higher than those of the parents.