Abstract: The origin of individual differences in reading ability is one of the most popular questions studied in the field of behavioral genetics. Here we used a meta-analysis on eighty empirical twin studies in reading ability to examine its genetic basis. Three new and fundamental findings have been observed. First, genetic factors have a moderate influence on general reading ability, reading-related processes (e.g., word recognition, spelling, and reading comprehension), and pre-reading cognitive skills (e.g., phonological processing, orthographic coding, rapid naming, and print knowledge). Second, components of the reading process are modulated by both general and specific genetic factors. Finally, the genetic overlap between reading ability and general cognitive ability and the genetic overlap between reading ability and mathematic ability are also moderate. Taken together, our meta-analysis indicates that twin studies play a critical role in exploring the genetic basis of individual differences in reading ability, complementary to studies based on rapidly growing molecular genetics.

Key words: reading ability, individual differences, twin studies, behavioral genetics