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Biomedical subjects

L Eaves

Publications and source records attributed to L Eaves.

99 records · Page 6Linked to original sources
PubMed1976

Genetic and environmental components of inconsistency and unrepeatability in twins' responses to a neuroticism questionnaire.

Responses of twins to an 11-item neuroticism scale extracted from questionnaires administered on two widely separated occasions were subjected to a genetic analysis. The results confirm earlier findings concerning the genetic determination of neuroticism and reveal that there is a genetic component in the inconsistency of the test measured by the interaction of subjects and test items. Variation within subjects over the 2-year period between tests was due purely to environmental factors specific to individuals. When a genetic model was fitted to the raw mean squares, there was no evidence that genetic variation was other than additive and no indication of an environmental component common to members of the same family.

Female↗
PubMed1976

A model for sibling effects in man.

A model is developed to specify the environmental effect of one sibling on another for a polygenic trait. Such effects are detectable in priniciple and the approach is illustrated with twin data relating to psychoticism. The relationship between the model and those employed in the treatment of kin selection is indicated.

Female↗
PubMed1976

The effect of cultural transmission on continuous variation.

Cultural transmission may depend on the non-genetic transfer of information from parent to offspring. The consequences of such cultural transmission for continuous variation are investigated theoretically for randomly mating populations. Cultural inheritance may act on genetical and environmental differences between individuals. The consequences for cultural inheritance of polygenic variation and variation due to chance environmental factors are considered. An equilibrium may occur in which the population variance and the covariances between relatives can be expressed as functions of estimable parameters of genetical and environmental variation. Whatever the ultimate origin of culturally inherited differences they are expected to lead to environmental differences between families ("E2" variation). In addition, if cultural transmission maintains differences due ultimately to segregation at many gene loci we may find genotype-environmental covariation is generated.

Cultural Characteristics↗
PubMed1975

The nature of extraversion: a genetical analysis.

A biometrical-genetical analysis of twin data to elucidate the determinants of variation in extraversion and its components, sociability and impulsiveness, revealed that both genetical and environmental factors contributed to variation in extraversion, to the variation and covariation of its component scales, and to the interaction between subjects and scales. A large environmental correlation between the scales suggested that environmental factors may predominate in determining the unitary nature of extraversion. The interaction between subjects and scales depended more on genetical factors, which suggests that the dual nature of extraversion has a strong genetical basis. A model assuming random mating, additive gene action, and specific environmental effects adequately describes the observed variation and covariation of sociability and impulsiveness. Possible evolutionary implications are discussed.

Adult↗
PubMedDate not supplied

Genetic and environmental influences on ratings of manifest anxiety by parents and children.

Parental reports and children's self-reports of manifest anxiety were obtained from a community-based sample of twin pairs on two occasions approximately 19 months apart, using the Revised Child Manifest Anxiety Scale (Reynolds & Richmond, 1978). In prior cross-sectional studies, a low degree of agreement between parent and child assessments of anxiety was found. Furthermore, parental reports were found to reflect a higher heritability than children's self-reports (Eaves et al., 1997; Thapar & McGuffin, 1995). The index of temporal stability was moderate for all informants (circa r = .5 to r = .6). To test whether the components contributing to the temporal stability differed between the informants, structural equation models were fitted to the data using the program, Mx: Statistical Modeling (Neale, 1995). The results showed substantial differences in genetic effects according to both gender and informant. For children's self-reports, temporal stability was largely a function of environmental effects, with genetic effects contributing a modest 20%, whereas for parental reports, temporal stability was largely a function of genetic effects. The heritability was higher for parental reports than for boys' self-reports and the genetic covariance between parents and their sons was near zero, indicating that they were reporting on quite different aspects of anxiety. However, for girls, heritability for maternal reports was lower than for self-reports, and the genetic covariance between mother and daughter was about the same as that between mothers and fathers, meaning that they were assessing the same genetically influenced aspect of anxiety. These results highlight the need to focus on gender differences.

Adult↗