BACKGROUND In order to develop informed approaches to prevention and treatment of illicit psychoactive substance use, abuse, and dependence, we need to understand the sources of individual differences in risk. METHODS In personal interviews with 1198 male-male twin pairs (708 monozygotic and 490 dizygotic) ascertained from a population-based registry, we assessed lifetime use, heavy use, and ...

BACKGROUND A possible familial component to fracture risk may be mediated through a genetic liability to fall recurrently. METHODS Our analysis sample included 186 female sibling-ships (n=401) of mean age 71.9 yr (SD=5.0). Using variance component models, we estimated residual upper-limit heritabilities in fall-risk mobility phenotypes (e.g., chair-stand time, rapid step-ups, and usual-paced ...

The purpose of this study was to examine, in a general population, the resemblance in eating behaviour between adolescents and their parents. This study was based on the first examination of a community-based epidemiological study in Northern France. Subjects were offspring aged 14-22 years (135 boys and 125 girls) and their parents (174 fathers and 205 mothers). The Three-Factor Eating Questio...

8.1.1 Variation in Phenotypic Traits ................................. 264 8.1.2 Familial Resemblance and Heritability ................... 264 8.1.3 The Special Case of Twins ...................................... 267 8.1.4 Embedding a Single Measured Gene Infl uencing a Continuous Trait ................................ 269 8.1.5 A Model for Variance Partitioning .......................... 269 ...

Although there is evidence that left ventricular (LV) function is genetically controlled, the contribution of familial factors to variation and covariation of LV diastolic filling, contractility, and structure is unknown. Single- and cross-trait sibling correlations were estimated using bivariate familial correlation models in 200 white (400 pairs) and 374 black (539 pairs) hypertensive sibship...

OBJECTIVE Although previous studies have suggested that sexual orientation is influenced by familial factors, which may be partly genetic, these studies have relied on unrepresentative and potentially biased samples. The authors attempted to estimate the role of genetic and environmental factors in the determination of sexual orientation in a more representative sample. METHOD Sexual orientat...

Genetic and environmental influences on systolic (SBP), diastolic (DBP), and mean arterial (MBP) blood pressure were examined using an expanded version of a path model in which parents and their singleton, twin, and adopted offspring were incorporated, and which also included an environmental index as an estimate of the underlying familial environmental component. Estimates of genetic heritabil...

The scientific debates on the future of human lifespan and its possible biological limits has revealed a great need for direct identification of longevity boundaries, if they really exist. The key question posed in this study is how can we possibly determine the age when human longevity starts? To address this problem, we studied the familial transmission of human lifespan from parents to daugh...