This paper explores the balance of genetic and environmental influences on dyslexia in generally supportive educational environments. Evidence from family studies suggests and research with identical and fraternal twins confirms the presence of strong genetic influences on dyslexia, though the way dyslexia is defined influences the degree of genetic influence. The behavioural genetic evidence is supported with molecular genetic evidence from DNA analyses suggesting regions on several different chromosomes where genes related to dyslexia are likely to be found. The behavioural and molecular genetic analyses are also applied to different component word reading skills (orthographic coding and phonological decoding) as well as to related language skills (phoneme awareness) to better understand the genetic and cognitive pathways to dyslexia.