Table 2.

Monozygotic (MZ) and dizygotic (DZ) twin correlations (95% CI), heritability and stability over two years, for the psychological variables and HCC.

	rMZ (115 pairs)	rDZ (183 pairs)	Heritabilitya	Two year Stabilityb (n = 146)
Perceived stress	0.51 (0.37–0.61)	0.29 (0.17–0.40)	0.54 (0.42–0.64)	0.61 (0.50–0.69)
Depressive symptoms	0.55 (0.43–0.65)	0.27 (0.13–0.40)	0.55 (0.42–0.65)	0.51 (0.37–0.62)
Neuroticism	0.53 (0.42–0.62)	0.31 (0.17–0.44)	0.56 (0.45–0.67)	0.58 (0.46–0.67)
Hair cortisol	0.66 (0.56–0.74)	0.42 (0.31–0.51)	0.72 (0.63–0.79)	0.32 (0.16–0.45)

Abbreviations: CI = confidence interval, rDZ = correlation between dizygotic twins, rMZ = correlation between monozygotic twins. All calculations were corrected for sex, age, age², sex x age, sex x age². ^aHeritabilities were estimated using the multivariate model (see Fig. 1). ^bTwo year stability was calculated as the correlation between time point 1 and time point 2.