. Author manuscript; available in PMC: 2014 Dec 1.

Published in final edited form as: J Speech Lang Hear Res. 2014 Jun 1;57(3):850–864. doi: 10.1044/2013_JSLHR-L-12-0240

Table 4. Univariate DeFries-Fulker extremes analysis: Etiology of LI at 4 years.

Classification	N		Transformed co-twin mean		Group heritability (95% CI)	Group shared environmentality (95% CI)	Group nonshared environmentality
Classification	MZ	DZ	MZ	DZ	Group heritability (95% CI)	Group shared environmentality (95% CI)	Group nonshared environmentality
Psychometric LI	226	115	.88	.69	.37 [0.15, 0.59]	.51 [.0.27, 0.74]	.12
Both psychometric LI and parent referral	71	51	.90	.33	>1.00 [0.74, 1.56]	.00	.00

Note. MZ = monozygotic; DZ = dizygotic; CI = confidence interval.