Background The contribution of hereditary factors to the causation of sporadic cancer is
unclear. Studies of twins make it possible to estimate the overall contribution of inherited genes …

Importance Estimates of familial cancer risk from population-based studies are essential
components of cancer risk prediction. Objective To estimate familial risk and heritability of …

Amajor component of variation in body height is due to genetic differences, but environmental
factors have a substantial contributory effect. In this study we aimed to analyse whether the …

Background Twin studies have provided evidence that both genetic and environmental
factors contribute to schizophrenia (SZ) risk. Heritability estimates of SZ in twin samples have …

Economic and rational‐choice theories suggest that individuals form unions or have
children because these decisions increase their subjective well‐being or “happiness.” We …

There is an intense search for longevity genes in both animal models and humans. Human
family studies have indicated that a modest amount of the overall variation in adult lifespan (…

Background A sedentary lifestyle remains a major threat to health in contemporary societies.
To get more insight in the relative contribution of genetic and environmental influences on …

Objective To examine the genetic and environmental influences on variances in weight,
height, and BMI, from birth through 19 years of age, in boys and girls from three continents. …

Background and Purpose— Few studies have assessed the overall importance of genetic
factors on stroke risk, and the results have been contradictory. We used a large, population-…

Questionnaire-based zygosity assessment in twins has generally been found to be valid. In
this report we evaluate sex- and age-differences in the validity of such questionnairebased …