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. Author manuscript; available in PMC: 2009 Jan 1.
Published in final edited form as: Learn Individ Differ. 2008;18(3):289–295. doi: 10.1016/j.lindif.2008.03.004

Table 3.

Intraclass Twin Correlations for Reading and Spelling at Kindergarten and Grade 1 Across Twin Samples

Australia
 United States
 Scandinavia
Variable MZr DZr MZr DZr MZr DZr
End of kindergarten
    Reading .90 .44 .89 .55 .84 .68
    Spelling .79 .45 .77 .58 .83 .58
End of Grade 1
    Reading .79 .27 .86 .45 .86 .49
    Spelling .79 .24 .76 .44 .79 .34