Beauchamp (1) presents a paradox: There is genetic selection favoring reduced time spent in education, or educational attainment, among the contemporary population of the United States, amounting to an expected decline of 1.5 mo per generation. Despite this finding, the average time spent in education among this population has increased by 24 mo per generation (1). This paradox is analogous to ...

Twin Research Volume 5 Number 6 pp. 554±571 Gene±environment interaction is likely to be a common and important source of variation for complex behavioral traits. Often conceptualized as the genetic control of sensitivity to the environment, it can be incorporated in variance components twin analyses by partitioning genetic effects into a mean part, which is independent of the environment, and ...

This article discusses the asymptotic behavior of likelihood ratio tests for nonzero variance components in the longitudinal mixed effects linear model described by Laird and Ware (1982, Biometrics 38, 963-974). Our discussion of the large-sample behavior of likelihood ratio tests for nonzero variance components is based on the results for nonstandard testing situations by Self and Liang (1987,...

Gene-environment interaction is likely to be a common and important source of variation for complex behavioral traits. Often conceptualized as the genetic control of sensitivity to the environment, it can be incorporated in variance components twin analyses by partitioning genetic effects into a mean part, which is independent of the environment, and a part that is a linear function of the envi...

Haseman & Elston (1972) introduced a sib pair method using classical regression analysis to detect linkage between a polymorphic marker locus and any quantitative trait locus. Most of the diseases mapped to date follow simple Mendelian, single locus transmission. But there are many familial diseases that do not follow simple Mendelian segregation, for example diabetes, several forms of cancer, ...

Use of variance-component estimation for mapping of quantitative-trait loci in humans is a subject of great current interest. When only trait values, not genotypic information, are considered, variance-component estimation can also be used to estimate heritability of a quantitative trait. Inbred pedigrees present special challenges for variance-component estimation. First, there are more varian...

In this paper, a linear mixed model which has two random effects is broken up into two models. This thesis gets the parameter estimation of the original model and an estimation’s statistical qualities based on these two models. Then many important properties are given by comparing this estimation with other general estimations. At the same time, this paper proves the analysis of variance estima...

F I S H E R (1918) subdivided genotypic variance (the variance due to genetic variation) into three components: (1) a part due to the average effects of genes (now called additive genetic variance) , ( 2 ) a part due to allelic interactions of genes that is called dominance variance, and (3) a part due to nonallelic interactions of genes that is called epistatic variance. A sound plant breeding...