The Ohio State University, OH, USA.
J Child Psychol Psychiatry. 2010 Jun;51(6):660-7. doi: 10.1111/j.1469-7610.2009.02204.x. Epub 2010 Jan 5.
Studies have suggested genetic and environmental influences on overall level of early reading whereas the larger reading literature has shown environmental influences on the rate of growth of early reading skills. This study is the first to examine the genetic and environmental influences on both initial level of performance and rate of subsequent growth in early reading.
Participants were drawn from the Western Reserve Reading Project, a study of 314 twin pairs based in Ohio. Twins were assessed via three annual home visits during early elementary school. Assessments included word identification, letter identification, pseudoword decoding, expressive vocabulary, phoneme awareness, and rapid naming. Measures were analyzed using latent growth curve modeling.
The heritability of initial performance (latent intercept) ranged from h(2) = .38 for word identification to h(2) = .72 for rapid naming. Shared environment ranged from c(2) = .11 for rapid naming to c(2) = .62 for word identification. The heritability of the rate of subsequent growth (latent slope) was statistically significant for rapid naming h(2) = .58 and phoneme awareness h(2) = .20. Shared environment accounted for nearly 100% of variance in rate of growth for word identification, letter identification and pseudoword decoding, and was statistically significant and large for phoneme awareness (c(2) = .80). Genetic variance for rapid naming and phoneme awareness latent slopes overlapped entirely with genetic variance on the intercepts. In contrast, one-third to two-thirds of the shared environmental variance on the slope was independent from the shared environmental variance on the intercept.
Genetic influences were related primarily to those already present at the initial level of performance. In contrast, shared environmental influences affecting rate of growth were both predicted by and independent from initial levels of performance. Results suggested that growth in early reading skills is amenable to family, school, or other environmental influences as reading skills develop.
研究表明，遗传和环境因素都会影响早期阅读的整体水平，而更广泛的阅读文献则表明环境因素会影响早期阅读技能的增长速度。本研究首次考察了遗传和环境因素对早期阅读初始水平和后续发展速度的影响。
参与者来自俄亥俄州西部储备阅读项目的 314 对双胞胎。双胞胎在小学早期通过三次年度家访进行评估。评估包括单词识别、字母识别、假词解码、表达词汇、语音意识和快速命名。使用潜在增长曲线模型对测量结果进行分析。
初始表现（潜在截距）的遗传度范围从单词识别的 h(2) =.38 到快速命名的 h(2) =.72。共享环境的范围从快速命名的 c(2) =.11 到单词识别的 c(2) =.62。随后生长速度（潜在斜率）的遗传度在快速命名 h(2) =.58 和语音意识 h(2) =.20 上具有统计学意义。共享环境几乎解释了单词识别、字母识别和假词解码的生长速度的 100%的方差，在语音意识上具有统计学意义且方差较大（c(2) =.80）。快速命名和语音意识的潜在斜率的遗传方差与截距的遗传方差完全重叠。相比之下，斜率上的共享环境方差的三分之一到三分之二与截距上的共享环境方差独立。
遗传影响主要与初始表现水平有关。相比之下，影响生长速度的共享环境影响既由初始表现水平预测，又与初始表现水平独立。结果表明，随着阅读技能的发展，早期阅读技能的增长可以适应家庭、学校或其他环境影响。
