Throughout modern science, a popular topic of research and discussion has been whether intelligence is hereditary. Twin studies have suggested a genetic influence on mathematical abilities, but if considered, environmental factors may also have played a role in the development of individuals' intelligence (Pinel, 1). Therefore, the dispute remains between nature and nurture: which of the two contributes to an individual's general intelligence and cognitive ability? Are some people born smarter than others or does everyone, despite mental disabilities, have the same opportunity to acquire intelligence? Research from various studies so far concludes that both are true; while intelligence is rooted in genetic influence, environmental factors play a crucial role in the extent of that influence. In a study published in 2009 in the Journal of Neuroscience, researchers used a new type of brain imaging scanner in a twin study to show that intelligence is strongly influenced by the quality of brain axons, which send signals throughout the brain. The faster the signaling, the faster the brain processes information, and since genes influence the integrity of axons, these genes indirectly play a role in an individual's intelligence. The study suggests that genes appear to influence intelligence by determining how well nerve axons are coated in myelin. The correlation with individual intelligence is based on the fact that the faster the myelin, the faster the nerve impulses and therefore the greater the brain's ability to process information. The researchers scanned the brains of 23 pairs of identical twins and 23 pairs of fraternal twins. Using the fact that identical twins share the same genes,… the focus of the article… genes and general intelligence. The results showed only a nominally significant association, which is lower than what would be expected by chance alone. The study then followed the methods of the 2011 study and, applying the same procedure in its analysis, estimated that the 630,000 SNPs in the data collectively accounted for 47% of the variance in general intelligence. The combined results of this study further strengthen the idea that intelligence is a highly polygenic trait. A more recent study published in 2013 in NeuroImage also worked on the basis of previous twin studies that have long suggested a genetic influence between specific candidate genes and intelligence. . This study examined the heritability of the trait by jointly estimating genetic and environmental contributions with a modified model that was classically used in twin studies.