Explored genetic and environmental etiologies of individual differences in printed word recognition and related skills in identical and fraternal twin 8- to 18-year-olds. Found evidence for moderate genetic influences common between IQ, phoneme awareness, and word-reading skills and for stronger IQ-independent genetic influences that were common between phoneme awareness and word-reading skills. Found that phonological and orthographic coding skills in word recognition had significant common and independent genetic influences. (Author/KB)