Entwined Lives Document Gallery

New England Journal of Medicine - Entwined Lives

Entwined Lives


New England Journal of Medicine
The study of twins is a fundamental tool of genetic epidemiology and thus is important to all medical and behavioral sciences. Even in this era of study of the human genome, the definition of phenotypic boundaries in many fields still requires refinement, and genetic and environmental influences require further exploration.

Twins: The Finest Natural Experiment

Twins: The Finest
Natural Experiment


Personality and Individual Differences
Twin studies have moved beyond the classic design described by Galton (1875). Natural experiments involving twins and twin-like individuals occur constantly, driven largely by artificial reproductive tech- nology and increased adoption rates. These events have produced exotic twin and sibling relations, e.g., virtual twins (same-age unrelated siblings) and twins reared apart (Chinese twin girls, abandoned and adopted separately). Research designs utilizing the unique genetic and social relatedness of such individ- uals can inform numerous behavioral domains. Many studies to be described were inspired by my asso- ciation with the Minnesota Study of Twins Reared Apart (1982–1991), directed by Bouchard.