The purpose of this study is to analyze genetic data from a large sample of twins and their families. Environments within and outside the families, as well as the individuals adjustment already have been investigated. We will how genes and environments interplay in adjustment. We will investigate (1) whether there is an association between specific genes and adjustment, (2) whether the associations are mediated by specific environments (gene-environment correlation), and (3) whether the associations are different in different environments (gene-environment interaction).
Medical, genetic, social, and humanistic research today tries to understand how genes and environments interplay in the development of behaviour, personality, and adjustment. The only way to clarify the complex nexuses is to use family studies and at the same time investigate both genes and important environments (above all family environments). This study will give unique possibilities for such analyses.
We have collected biological samples of 3,606 individuals (twins, their spouses, and adolescent children), and will now extract DNA and genotype these individuals. We already have extensive data on their environments (socioeconomic status, social support, life events), family processes (marital, sibling, and parent-child relationships), and adjustment (personality, behaviour, drug use, mental health).