Genetic simplex modeling of personality in adolescent Australian twins N.A. GILLESPIE 1, D. M. EVANS 1, N.G. MARTIN 1 1 Queensland Institute of Medical Research and University of Queensland, Joint Genetics Program, Brisbane, Australia. Supported by Queensland Cancer Fund, Cooperative Research Centre for Discovery of Genes for Common Human Diseases, and NHMRC grants &

Modeling personality change Eaves, Eysenck & Martin (1989) Adult personality - High of genetic continuity over time ! Effect stronger in Neuroticism vs Extraversion Genetic continuity in adolescents? Simplex modeling (Boomsma, 1989)

Genetic Simplex modeling Autoregressive model Structural equation model η i = β i η i-1 + ζ i var (η i ) = β i 2 var (η i-1 ) + var (ζ i ) ζ i-1  i-1 Y i-1 YiYi Y i+1 ζ i ζ i+1 λ i-1 λ i λ i+1 ε i-1 β i β i+1 ii  i+1 ε iε i ε i+1 Measurement model Y i = λ i η i + ε i var (Y i ) = λ i 2 var (η i ) + var (ε i )

TWIN 1 TWIN 2

Sample Twin Mole and Twin MAPS projects Assess the genetic / environmental etiology of Melanocytic Naevi (common moles) in twins aged 12 & 14 years + Cognition at items JEPQ - Psychoticism (P) - Extraversion (E) - Neuroticism (N)- Lie (L)

Data Normal weighted by sex and age Structural equation modeling using ML analysis of individual observations performed in Mx Raw continuous data methods Assumptions of mean and variance homogeneity by twin order and zygosity (and necessarily by sex and age)

Polychoric test-retest correlations

Twin pair polychoric correlations Consistent with a genetic hypothesis ! Univariate & Multivariate results AE best fitting model

P12P14P16 ε1ε1 ε2ε2 ε3ε3 ζ A2 ζ A3 111 E1E1 ζ E1 ζ E2 ζ E3 β E2 β E3 E2E2 E3E3 ζ A β A2 β A3 A1A1 A2A2 A3A3 Psychoticism AE Simplex model

ζ A2 111 E1E1 ζ E1 ζ E2 ζ E3 β E2 β E3 E2E2 E3E3 ζ A β A2 β A3 A1A1 A2A2 A3A3 Psychoticism Drop genetic 16 years P12P14P16 ε1ε1 ε2ε2 ε3ε3

ζ A3 111 E1E1 ζ E1 ζ E2 ζ E3 β E2 β E3 E2E2 E3E3 ζ A β A2 β A3 A1A1 A2A2 A3A3 Psychoticism Drop genetic 14 years P12P14P16 ε1ε1 ε2ε2 ε3ε3

Psychoticism - Best fitting Simplex model ε1ε P12 A1A1 E1E1 P14 A2A2 E2E2 P16 A3A3 E3E3 ε1ε1. 36 ε1ε1 ζ A2. 12 ζ A1. 37 ζ A ζ E1. 15 ζ E2. 06 ζ E

Extraversion AE Simplex model E12E14E16 ε1ε1 ε2ε2 ε3ε3 ζ A2 ζ A3 111 E1E1 ζ E1 ζ E2 ζ E3 β E2 β E3 E2E2 E3E3 ζ A β A2 β A3 A1A1 A2A2 A3A3

Extraversion Drop genetic 16 years E12E14E16 ε1ε1 ε2ε2 ε3ε3 ζ A2 111 E1E1 ζ E1 ζ E2 ζ E3 β E2 β E3 E2E2 E3E3 ζ A β A2 β A3 A1A1 A2A2 A3A3

Extraversion Drop genetic 14 years E12E14E16 ε1ε1 ε2ε2 ε3ε3 ζ A3 111 E1E1 ζ E1 ζ E2 ζ E3 β E2 β E3 E2E2 E3E3 ζ A β A2 β A3 A1A1 A2A2 A3A3

Extraversion - Best fitting Simplex model ε1ε E12 A1A1 E1E1 E14 A2A2 E2E2 E16 A3A3 E3E3 ε1ε1. 23 ε1ε1 ζ A2. 12 ζ A ζ E1. 35 ζ E2. 18 ζ E

N12N14N16 ε1ε1 ε2ε2 ε3ε3 ζ A2 ζ A3 111 E1E1 ζ E1 ζ E2 ζ E3 β E2 β E3 E2E2 E3E3 ζ A β A2 β A3 A1A1 A2A2 A3A3 Neuroticism AE Simplex model

N12N14N16 ε1ε1 ε2ε2 ε3ε3 ζ A2 111 E1E1 ζ E1 ζ E2 ζ E3 β E2 β E3 E2E2 E3E3 ζ A β A2 β A3 A1A1 A2A2 A3A3 Neuroticism Drop genetic 16 years

N12N14N16 ε1ε1 ε2ε2 ε3ε3 ζ A3 111 E1E1 ζ E1 ζ E2 ζ E3 β E2 β E3 E2E2 E3E3 ζ A β A2 β A3 A1A1 A2A2 A3A3 Neuroticism Drop genetic 14 years

Neuroticism - Best fitting Simplex model ε1ε N12 A1A1 E1E1 N14 A2A2 E2E2 N16 A3A3 E3E3 ε1ε1. 22 ε1ε1 ζ A2. 11 ζ A1. 36 ζ A ζ E1. 39 ζ E2. 22 ζ E

Lie AE Simplex model L12L14L16 ε1ε1 ε2ε2 ε3ε3 ζ A2 ζ A3 111 E1E1 ζ E1 ζ E2 ζ E3 β E2 β E3 E2E2 E3E3 ζ A β A2 β A3 A1A1 A2A2 A3A3

Lie Drop genetic 16 years ζ A2 111 E1E1 ζ E1 ζ E2 ζ E3 β E2 β E3 E2E2 E3E3 ζ A β A2 β A3 A1A1 A2A2 A3A3 L12L14L16 ε1ε1 ε2ε2 ε3ε3

Lie Drop genetic 14 years ζ A3 111 E1E1 ζ E1 ζ E2 ζ E3 β E2 β E3 E2E2 E3E3 ζ A β A2 β A3 A1A1 A2A2 A3A3 L12L14L16 ε1ε1 ε2ε2 ε3ε3

Lie - Best fitting Simplex model ε1ε L12 A1A1 E1E1 L14 A2A2 E2E2 L16 A3A3 E3E3 ε1ε1. 24 ε1ε1 ζ A2. 10 ζ A1. 45 ζ A ζ E1. 28 ζ E2. 23 ζ E

Discussion Uni- and multivariate analyses Small BUT significant genetic 12 & 14 years Genes which effect personality traits at all three ages + New genetic innovations Different environments are salient at different ages

Limitations Normal weighted data Removes age and sex effects Does not capture  phenotypic variance with age Analyses based on transformed data to remove skewness Equivalent results ! Sex limitation Evidence of general sex limitation for Neuroticism at 16 years

Home Simplex model Neuroticism final model