. Author manuscript; available in PMC: 2011 Oct 25.

Published in final edited form as: Behav Genet. 2010 Feb 3;40(2):178–185. doi: 10.1007/s10519-010-9337-1

Table 2.

Twin correlations and heritability estimates for event-related brain potentials (ERPs) evoked by facial expressions of emotion

ERP component	r_MZ (n = 47)	r_DZ (n = 51)	a² (95% CI)	e² (95% CI)
N240, neutral	.64**	.22	.60 (.40–.73)	.40 (.27–.60)
N240, fear	.61**	.41**	.64 (.46–.76)	.36 (.24–.54)
N240, happy	.57**	.22	.55 (.34–.71)	.45 (.29–.66)
P3, neutral	.49**	.12	.42 (.21–.59)	.58 (.41–.79)
P3, fear	.61**	.19	.56 (.36–.71)	.44 (.29–.64)
P3, happy	.70**	.15	.62 (.47–.75)	.38 (.25–.55)
P600 (face identity)	.30*	.10	.28 (.02–.51)	.72 (.49–.98)

r_MZ and r_DZ are intrapair correlations for MZ and DZ twins, respectively. Variance component estimates are based on the best-fitting “AE” model for all variables; a² is the proportion of total phenotypic variance explained by genetic factors (heritability); e² is the proportion of variance due to environmental factors (95% confidence intervals of the maximum likelihood estimates of the variance components are shown in brackets)