The relative proportion of additive and non-additive variation for complex traits is important
in evolutionary biology, medicine, and agriculture. We address a long-standing controversy …

Twins are an important resource for evaluating the relative contribution of genetic and
environmental factors in determining a phenotype. During the last decades, a number of twin …

Background: Although the clinical utility of categorically defined attention‐deficit
hyperactivity disorder (ADHD) is well established, there is also strong evidence supporting …

Human wellbeing is influenced by personality traits, in particular neuroticism and
extraversion. Little is known about which facets that drive these associations, and the role of …

BackgroundLittle is known about the pattern of genetic and environmental influences on
symptoms of anxiety and depression (SxAnxDep) from childhood to early adulthood …

BackgroundThe personality disorders (PDs) in the 'dramatic'cluster B [antisocial (ASPD),
histrionic (HPD), narcissistic (NPD) and borderline (BPD)] demonstrate co-morbidity …

Twin-and family studies have shown variations in the heritability estimates of bipolar
disorder (BPD). The current study uses an updated statistical methodology for heritability …

Power is a ubiquitous, though often overlooked, component of any statistical analyses.
Almost every funding agency and institutional review board requires that some sort of power …

The present study is the first long‐term longitudinal examination of the etiology of individual
differences in language from early childhood through to adolescence. We applied a …

A foundational question in the social sciences concerns the interplay of underlying causes in
the formation of people's political beliefs and prejudices. What role, if any, do genes …