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Biomedical subjects

L Eaves

Publications and source records attributed to L Eaves.

At least 73 records · Page 4Linked to original sources
PubMed1993

A twin study of recent life events and difficulties.

OBJECTIVES: To examine the role of genetic and familial-environmental factors in the origin of stressful life events. DESIGN: Self-report questionnaires describing stressful life events in the last year. PARTICIPANTS: Both members of 2315 twin paris ascertained from the population-based Virginia Twin Registry. RESULTS: Life events were modestly but significantly correlated in twin pairs, and correlations in monozygotic (MZ) twins consistently exceeded those in dizygotic (DZ) twins. For total life events, the best-fitting twin model indicated that familial-environmental and genetic factors each accounted for around 20% of the total variance. Individual life events could be best divided into "network events" (directly affecting individuals in the respondent's social-network) where twin resemblance was due solely to the familial environment, and "personal" events (directly affecting the response) where most twin resemblance was the result of genetic factors. CONCLUSIONS: While neither genes nor familial environment is likely to directly produce life events, personal and social factors that predispose to life events are substantially influenced by an individual's genetic and family background. These results, which suggest that stressful life events reflect more than random influences, may have important implications for our understanding of the relationship between stressful life events and psychopathology.

Adolescent↗
PubMed1992

Genetic and environmental effects on type A scores in monozygotic twin families.

Monozygotic (MZ) twin pairs with spouses and children, altogether 787 subjects, completed the Jenkins Activity Survey (JAS). The observed correlations for the various sets of relationships fitted well with biometric models including only parameters for additive genetic effects and, for Type A and Job Involvement, assortative mating. There was no evidence of effects of the family environment (cultural transmission) or genetic dominance (nonadditivity). For all but the Hard Driving and Competitive scale, there was evidence of effects of sex-specific genes. The heritability estimates were, for males and females, respectively, .33 and .39 for Type A, .36 and .48 for Job Involvement, .20 and .52 for Speed and Impatience, and .13 (both sexes) for Hard Driving and Competitive. The estimates given here are deflated by measurement errors and should probably be corrected by multiplying by values in the neighborhood of 1.3. Even after correction, the results suggest that individual differences for Type A and related traits depend more on nonfamilial environment than on genes.

Adult↗
PubMed1991

Pedigree analysis of Eysenck Personality Questionnaire (EPQ) scores in monozygotic (MZ) twin families.

MZ twins with spouses and children, altogether 811 subjects, completed the Eysenck Personality Questionnaire (EPQ). For extraversion (E), neuroticism (N), and lying (L), models including only additive genetic effects fitted well to the observed sex-specific correlations for the various sets of relationships. There was no evidence of sex differences for any parameter estimate for E, N, and L. The fit for E improved significantly after including dominance, and the fit for L improved significantly after including assortative mating. A model specifying genetic additive and dominance effects and assortative mating fitted well to the Psychoticism (P) data, but the fit improved significantly when a parameter for cultural transmission from fathers to daughters were included. Except for this, there was no evidence of cultural transmission for any scores. The heritabilities for the best-fitting models were .53 (E), .36 (N), .43 (L), and .39 (P). The latter includes almost only nonadditive, and no additive, variance, suggesting an overestimation of this effect due to random fluctuation or environmental sibling effect misinterpreted as dominance.

Adult↗