The early onset of alcohol and tobacco use has been associated with increased risk for later substance abuse and dependence problems. This study investigated genetic and environmental influences on age at onset of alcohol and tobacco use by examining twin resemblance for several retrospectively reported onset milestones including age at first use, age at first alcohol intoxication experience, a...

CONTEXT Drug abuse (DA) strongly runs in families. Does this result solely from genetic factors or does the family environment contribute? OBJECTIVE To determine the familial environmental contribution to the risk for DA. DESIGN Follow-up in 9 public databases (1961-2009) in siblings and spouses. SETTING Sweden. PARTICIPANTS A total of 137 199 sibling pairs and 7561 spousal pairs containing a p...

Family resemblance for normal pulmonary function as measured by forced vital capacity and one second forced expiration volume is assessed using a path analysis model which incorporates sex differences in transmissibility of the phenotype from parents to offspring as well as in the effect of a correlated shared-sibling environment. Application of this model, called XTAU, to familial correlations...

This article discusses a puzzle, the heart of which is this question: How it that real individuals can resemble fictional individuals? It seems any answer given by one who has taken stand on ontology will come with significant drawbacks. An Anti-Realist have to explain, or explain away, apparent truth our positive assertions resemblance, while Realist how we are understand resemblance in light ...