This study examined common and unique genetic and environmental influences on weekend drinking and weekday drinking reported by US male and female adult participants (mean age = 43.9). Data from 96 monozygotic and 82 dizygotic twin pairs were used to estimate bivariate biometric models of daily levels of weekend and weekday drinking volume. Weekend and weekday drinking volume scores were calcul...

PURPOSE Educational attainment has been proposed as one of the most consistent environmental risk factors associated with myopia. The Genes in Myopia (GEM) twin study is the first myopia twin study to determine the relative genetic contribution in educational attainment as well as assessing the shared genetic and environmental factors between educational attainment and refraction through struct...

BACKGROUND It is not known if a subject's characteristic level of self-rated depression symptoms index their genetic or environmental liability to major depressive disorder when measurement error and other occasion-specific influences are taken into account. METHOD Monozygotic (N = 408) and dizygotic (N = 295) adult female twin pairs from a population-based registry were surveyed twice with a...

There is mounting evidence of etiologically driven distinctions between aggressive (AGG) and non-aggressive rule-breaking (RB) forms of antisocial behavior. To date, however, these differences remain somewhat speculative. The current meta-analysis of twin and adoption studies sought to clarify these distinctions by comparing meta-analytic estimates of genetic, shared environmental, and non-shar...

OBJECTIVE To review findings on attention-deficit/hyperactivity disorder and attention problems (AP) in children, adolescents, and adults, as established in the database of the Netherlands Twin Register and increase the understanding of stability in AP across the lifespan as a function of genetic and environmental influences. METHOD A longitudinal model was fitted on Netherlands Twin Register...

BACKGROUND Childhood emotional and behaviour problems are antecedents for later psychopathology. This study investigated genetic and environmental influences shaping the longitudinal association between childhood emotional and behaviour problems and specific PEs. METHOD In a community-based twin sample, parents reported on emotional and behaviour problems when twins were ages 7 and 12 years. ...

Generalized anxiety disorder (GAD), panic disorder (PD) and post-traumatic stress disorder (PTSD) often co-occur. We investigated whether and to what degree genetic and environmental contributions overlap among symptoms of GAD, symptoms of PD and PTSD. Subjects were 3327 monozygotic and dizygotic male-male twin pair members of the Vietnam Era Twin Registry who participated in a 1992 telephone a...

We assessed the ability of present-day environmental factors to explain the nonoverlapping range boundaries of Skistodiaptomus copepods in the northeastern USA. Variance partitioning using partial canonical correspondence analysis (CCA) attributed 21% of the variance in species occurrences to spatial location, 20% to spatially structured environmental variation, and 12% to environmental factors...

We examined the contribution of genetic and environmental influences on the stability of withdrawn behavior (WB) in childhood using a longitudinal multiple rater twin design. Maternal and paternal ratings on the withdrawn subscale of the Child Behavior Checklist (CBCL) were obtained from 14,889 families when the twins were 3, 7, 10 and 12 years old. A longitudinal psychometric model was fitted ...

More education is associated with healthier smoking and drinking behaviors. Most analyses of effects of education focus on mean levels. Few studies have compared variance in health-related behaviors at different levels of education or analyzed how education impacts underlying genetic and environmental sources of health-related behaviors. This study explored these influences. In a 2002 postal qu...