This chapter attempts to broadly outline the current understanding of the etiology of intelligence and intelligence-related processes. First, it describes the major concepts that have primarily guided studies of the etiological bases of intellectual abilities and disabilities. Then, the chapter discusses the state of the field's understanding of cases of intellectual abilities and disabilities. A point of view on the Chinese initiative as presented in the CNN electronic publication is described. The chapter describes the major concepts that have been and are used to explore the connection between the genes and intelligence. The evidence pertaining to observations that the genome is a major source of the variations in individuals' intellectual abilities and disabilities is discussed. Studies of various indicators of information processing speed have been prominent in the field of intelligence due to the observation that these indicators reliably correlate with various aspects of intelligence, especially, with the g factor.