Book excerpt: Research Paper (postgraduate) from the year 2017 in the subject Medicine - Human Genetics, grade: 1, Egerton University, language: English, abstract: In an attempt to determine the factors that influence intelligence in humans, psychologists have investigated the issue from two principal perspectives: nature and nurture. As a result, research studies on these aspects have confirmed that both nature and nurture influences the development of intelligence. According to Heffner, genetic factors have been identified as the influential forces of nature that shape intelligence, whereas environmental factors influence intelligence through exposure or rather nurture. In both schools of thought, it is apparent that tests for intelligence are aimed at determining the level of intelligence through the use of Intelligence Quotient (IQ) test. Similarities and differences in IQ among individuals explain the degree at which genetics and environment influences development of intelligence. Therefore, this research paper discusses nature-nurture basis of intelligence.