Table 3.

Individual-Level and Co-Twin Control Analyses of Age-29 MPQ Normal-Range Personality Traits and Age-34 DAS Romantic Relationship Satisfaction

				Co-Twin Control Models
		Individual-Level Models		Twin Difference Effects
		Beta (SE)	p value	Beta (SE)	p value
MPQ (age 29)	Stress reaction	−0.12 (.04)	.003	−0.05 (.07)	.452
	Alienation	−0.20 (.05)	< .001	−0.21 (.08)	.008
	Aggression	−0.17 (.05)	.002	−0.08 (.09)	.396
	Well being	0.20 (.04)	< .001	0.02 (.08)	.793
	Control	0.12 (.05)	.014	0.22 (.07)	.002
	Harm avoidance	0.05 (.04)	.248	–	–

Notes. Results of individual-level linear mixed models (LMMs) and co-twin control models. Individual-level analyses examined associations between normal-range personality, measured using the Multidimensional Personality Questionnaire (MPQ), at age 29 and romantic relationship satisfaction, measured using a brief version of the Dyadic Adjustment Scale (DAS), at age 34; individual-level analyses consider twins as individuals and were conducted in the full sample, N = 230 twins, and models included random intercepts at the twin-pair level to account for the interdependence of the twin data. Significant individual-level associations were followed up using co-twin control analyses to examine twin difference effects (co-twin control analyses were not conducted for nonsignificant individual-level associations, noted in the table with a dash); co-twin control analyses consider differences within a twin pair and were conducted in the sample of intact twin pairs, n = 206 twins (from 103 intact twin pairs), with random intercepts at the twin-pair level to account for the twin data. All models included participant age and sex as covariates.