We partitioned early childhood reading into genetic and environmental sources of variance and examined the full distribution of ability levels from low through normal to high as computed by quantile regression. The full sample comprised twin pairs measured at preschool (n = 977), kindergarten (n = 1028), grade 1 (n = 999), and grade 2 (n = 1000). Quantile regression analyses of the full distribution of literacy ability showed genetic influence in all grades from preschool to grade 2. At preschool, the low end of the distribution had higher genetic influence than the high end of the distribution and the shared environment influence was the opposite. These shared environment influences of preschool became insignificant with formal schooling. This suggests that higher scores in pre-literacy skills (preschool) are more influenced by shared environment factors, though these are short-lived. This study discusses the factors that may be influencing the results.

中文翻译：

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基因和环境对阅读能力分布的不同影响。

我们将儿童早期阅读分为遗传和环境差异来源，并根据分位数回归计算了能力水平从低到正常到高的完整分布。完整样本包括在学龄前（n = 977），幼儿园（n = 1028），1年级（n = 999）和2年级（n = 1000）时测量的双胞胎。对识字能力的全部分布进行的分位数回归分析显示，从学龄前到2年级的所有年级都有遗传影响。在学龄前，低端分布的遗传影响高于高端分布，而共享环境的影响则相反。在正规学校中，学龄前儿童的这些共同的环境影响变得微不足道。这表明较高的识字能力（学前班）成绩受共享环境因素的影响更大，尽管这些都是短暂的。这项研究讨论了可能影响结果的因素。