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. Author manuscript; available in PMC: 2013 Mar 28.
Published in final edited form as: Child Dev. 2011 Oct 25;82(6):2123–2137. doi: 10.1111/j.1467-8624.2011.01658.x

Table 3.

Intraclass twin correlations (ICC) and proportion of variance due to genetic (A), shared environmental (C), and nonshared environmental (E) factors for reading achievement and independent reading (with 95% confidence intervals in parentheses)

MZ DZ Variance components

ICC n ICC n A E
Print 1 .59
(.42, .72)
73 .00
(.00, .17)
93 .62
(.45, .73)
.38
(.27, .55)
Read1 . 88
(.81, .92)
81 .42
(.25, .57)
104 .90
(.85, .92)
.10
(.08, .15)
Print 2 .61
(.40, .76)
48 .00
(.00, .21)
61 .55
(.36, .68)
.45
(.32, .64)
Read2 .77
(.65, .86)
61 .47
(.28, .62)
79 .75
(.69, .80)
.25
(.20, .31)

Note: n = Number of pairs. MZ = Monozygotic twins; DZ = Dizygotic twins. Read1, Print1 = reading achievement and independent reading at Age 10; Read2, Print2 = reading achievement and independent reading at Age 11.